INDUS VALLEY CIVILIZATION (HARAPPAN CIVILIZATION)

INTRODUCTION

             Harappan civilization is considered to be first urbanization in India.Material characteristics (Town planning,pottery work,arts and crafts),population census,economic activities,prospering in trade and commerce,technological advancement etc are some of the characteristics of the urbanised civilization and Harappan civilization had all of them.This civilization was a bronze age civilization and this the earliest known urban culture in Indian subcontinent.

Indus valley civilization

            

KEY AREAS TO BE COVERED:-

• DISCOVERY OF INDUS VALLEY CIVILIZATION

• Stage of evolution

• Origin and extent

• Debate on origin of Indus/Harappan civilization

• WHY IT IS CALLED HARAPPAN CIVILIZATION

• ORIGIN OF SETTLED VILLAGE AND AGRICULTURE

• THE EARLY HARAPPAN PERIOD

• Southern Afghanistan

• Quetta Valley

• Central and Southern Balochistan

• The Indus Areas

1.   Amri

2. Kot Diji

3. Mehrgarh

4. Rahman Dheri

5. Tarkai Qila

•      Punjab And Bahawalpur

•     Kalibangan

• IMPORTANT SITES OF INDUS VALLEY CIVILIZATION(MATURE HARAPPAN PERIOD).

1. Mohenjodaro

2. Harappa

3. Kalibangan

4. Dholavira

5. Lothal 

6. Rakhigarhi

7. Ganeriwala

8. Banawali

9. surkotada          

•  SETTLEMENT PATTERN OF INDUS VALLEY CIVILIZATION

• SOCIAL LIFE

• ESTABLISHMENT OF TRADING NETWORKS(ECONOMY)

• Intra-Regional Trade

• Trade with Persian Gulf and Mesopotamia

•  RELIGION AND RELIGIOUS PRACTICES

• POLITY

• DECLINE OF HARAPPAN CIVILIZATION

DISCOVERY OF INDUS VALLEY CIVILIZATION

  About 5000 years ago,some people from eastern foothill of Balochistan,started moving into the river valleys of Indus and Saraswati.They settled in various sites of these valleys.Hence,slowly and gradually ,they evolved a civilization called as harappan or Indus Valley Civilization.

• Charles Masson,an English man, visited a village named Harappan in Western punjab(Pakistan) in 1826.He found an old settlement and believed that this city belongs to the time of Alexander the Great.

• In 1853,Alexander Cunningham came to this place and collected some archaeological objects from this site but he could not determine  to which period of history they really belonged.He  believed that these objects were probably from outside India and the city was about a thousand years old.

• Much later in 1921,the site of Harappa was appreciated when an Indian archeologist,Daya Ram Sahani,started excavating it.At about the same time R.D Banarjee ,a historian excavated the site of Mohenjodaro in Sindh.

•  In 1924,  another archaeologist John Marshall reported about Harappa.According to him,. this civilization was as old as the civilizations of Egypt and Mesopotamia.John Marshall was the first to use the term Indus Civilization.

     The Stage of Evolution

5550BC-3500BC	Neolithic	In Baluchistan and Indus plains settlement like Mehrgarh and Kili Ghul Muhammad emerged. Pastoralism with limited cultivation leads to seasonal occupation of the villages ,permanent villages emerge. Knowledge of wheat,barley,dates, cotton and Sheep,goats and cattle Evidence of mud houses,pottery and craft production.
3500BC-2600BC	Early Harappan Period	Many more settlements emerged in the hills and plains.Largest no of villages occurred during this period. Use of copper,wheel and plough. Evidence of granary,defensive wall,and long distance trade . Emergence of uniformities in pottery tradition throughout the Indus Valley. Origin of motifs as pipal,humped bull,cobras ,horned deity etc
2600BC-1800BC	Mature Harappan period	Emergence of large cities,uniforms types of bricks,weights,beads,seals and pottery.planned township and long distance trade
1800BC Onwards	Late Harappan period	Many Harappan sites abandoned,inter regional exchange decline,i9nternal trade decline,continuation of Harappan craft and pottery tradition.

ORIGIN AND EXTENT

   Indus valley civilization marks the 1st phase of urbanization in Indian subcontinent.The earliest evidence of the civilization was accidentally discovered by A.cunningham in 1853.Historians give different estimates about the chronology of Indus valley civilization.

• John Marshall   3250 BC-2750BC

• Piggot and Wheeler    :2350BC-1750BC

• Watler Fairserns         :2000BC-1500BC

• DP Agrawal                 :2300BC-1750

The Indus Valley Civilization covered the whole Punjab(both in India as well as in Pakistan) ,Haryana ,parts of Western UP,Northern Rajasthan ,Sindh,Most of Gujrat,parts of north east and southern Balochistan

DEBATE ON ORIGIN OF IVC/HARAPPAN CIVILIZATION

•   John Marshall,V.Gordon,Stuart Piggot,Nani Gopal Majumdar emphised on Indigenous origin of the Civilization.

• Sir Mortimer Wheeler Believed that the civilization came from Mesopotamia.It was an extension of Mesopotamia Civilization

• Heine Geldern considered the cities of Harappa and Mohenjodaro to be colonial cities.According to him,.It was an extension of Mesopotamia Civilization.

• BB Lal,BK Thaper in their excavation of Kalibangan ,all three Majundar Lal and Thapper pointed out that Indus culture was an indegenous origin.

• It belongs to the Chalcolithic or Bronze age as Harappans develop new techniques in metallurgy and produce copper ,bronze and lead.

WHY IT IS CALLED HARAPPAN CIVILIZATION

•  Along with the discovery of Harappa, nearly thousand settlements having similar

traits, have been discovered.Historian named it the 'Indus Valley Civilization' because

most of the settlements were discovered in the plains of the river Indus and

its tributaries.

• According to archeological convention when an ancient culture is described it is named after the modern name of the site.Though Harappan site was discovered first i.e in 1921 so Indus valley civilization is called Harappan civilization.

ORIGIN OF SETTLED VILLAGE AND AGRICULTURE

• Emergence of early agricultural communities comes from a place called Mehrgarh in the Balochistan provinces of Pakistan.Beginning as a seasonal camp the place turned into a settled village in the 5th millennium B.C. itself.

•  People in this place were growing wheat, barley. cotton and dates and tending sheep, goat and cattle.

•  Mehrgarh is located in the alluvial plains of the Indus join the uneven hilly plateau ,of the Indo-lranian border land. People of Mehrgarh lived in mud houses having  five to six rooms..

•  By the middle of the 3rd millennium B.C. many small and large villages had sprung    up around the Indus,Baluchistan and Afghan area.

•   The better known settlements among them are Kili Ghul Muhammad,

Mundigak in Afghanistan and  Jalilpur near Harappa.. 

• These  agriculturists learnt to exploit the highly fertile floodplains of the Indus there was a sudden expansion in the size and numbers of villages. These agriculturists gradually  exploit the Indus plains and to contro! the flooding of the Indus.Surplus in production led to an increase in the number of settlements in

Sindh, Rajasthan, Baluchistan and other areas.. All this led to the development small

towns. The period of this new development is called 'the Early Harappan' because

of certain uniformities found all over the Indus

     THE EARLY HARAPPAN PERIOD

The settlements just before the emergence of the Harappan civilization is called  'The Early Harappan Period because they believe that this was the formative epoch of the Harappan Civilization when certain trends of cultural unification are in evidence. '

1.  Southern Afghanistan( Mundigak:)

•  evidence of a defensive wall, used of sun dried bricks

• A  variety of pottery, Terracotta female figurines , semi precious stones such as  lapis-lazuli and steatite,have also been discovered at this place.

   2. Quetta Valley(South east of Mundigak)

• Large house having a brick wall is found in a place called Damb sadaat.

•  Varieties of painted pottery ,seals and copper objects ,yielded female figurines have also been discovered at this place. have also been discovered at this place.

      3.Central and Southern Balochistan

• Important sites like Anjira, Togau, Nindowari and Balakot give us some idea of the early Harappan societies.

• Many of the sites show evidence of contact with Persian Gulf. In Balakot the people who first inhabited the place were using potteries similar to those used in other contemporary villages in Balochistan

• The people of the entire Baluchistan province were using similar kinds of pottery.

• They used  motifs on their pottery like the.humped bulland Pipal which continued into the Mature Harappan phase.

        4. The Indus Area

               The Indus alluvial plains become the focal point of change,by the middle of the 4th    millennium B.C.Small and large settlements came into existence on the banks

of the Indus and Ghaggar-Hakra and became the core region of the Harappan

Civilization..

Amri(Sindh Provinces)

• people living in houses of stone and mud brick, using wheel-made pottery.

• They had fortified their settlements before the coming of the Harappan civilization.

• They painted such animal motifs as the humped Indian bulls on their pottery and this motif was very popular during the 'Mature Harappan' phase

Kot Dii(left bank of the river Indus is the site of Kot Diji)

• massive defensive walls , wheel-thrown pottery having decorations of plain bands of dark brownish paint  have also been discovered at this place.

• 'Early Harappan' culture, probably similar to that of Kot Diji.

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           Mehrgarh(Pakistan)

•  Earlier  Harappan urbanisation, the people of Mehrgarh had established a prosperous township .  

• various kinds of beads of stones were used by them such as Lapis-lazuli, seatite etc.

• seals and sealing,similar kinds of potteries, terracotta figurines and objects of Copper and stone indicate that these people were in close contact with the neighbouring towns of Iran.

         Rahman Dheri(Northwards of the river Indus)

•  Oblong in shape with houses, streets and lanes laid out in a planned fashion, beads of turquoise and lapis lazuli ,pottery,Seals, tools made of stone, copper and bronze have also been found.

        Tarkai Qila(North west frontier provinces)

• evidence of fortification,large samples of grains which included many varieties of wheat and barley, lentils and field pea.Tools for harvesting, huge factory site for making stone tools, lapis lazuli and terracotta figurines have also been discovered.

       Punjab and Bahawalpur (western Punjab) 

• This site belongs to the pre-Harappan period.

       Kalibangaon( north Rajasthan)

•  People lived in houses of mud bricks, The pottery used by them was different in shape and design from that of other areas.

Important sites of Indus Valley Civilization(Mature Harappan Period)

.                     A number of sites and settlements have been found mainly in the fertile region of the Indus river and its tributaries. Indus Valley Civilization developed into early and mature cultures. Some  early Harappan communities developed into large urban centres including Mohenjo Daro, Harappa ,Rakhigarhi,Ganeriwala ,Dholavira ,Kalibangan Rupa and Lothal.

Mohenjo Daro. 

                  Mohenjo Daro( the mound of Dead) is situated in the Larkana district of Sindh(Pakistan ).this city was situated on the right bank of river Indus. 

   

                   Estimated population of Mohenjo-daro in mature Harappan age was between 41000 to 35000 .Two major area here:a high citadel to the west consisting of a large granary and a water tank or a bath and a lower city of domestic dwelling to the East-this was the residential Unity constructed on a grid pattern. 

                Urban planning ,and uniform and careful executed layouts for Water Supply and Drainage. The great bath of Mohenjo Daro was the most important public place located at the centre of Citadel. 

                 The great granary was the largest building which was located within the Citadel. Great granary is the largest building in the Indus valley civilization which is 45.71m long and 15.23m wide.Mohenjo Daro was excavated in 1922 by R D Banerjee.

Harappa

                 It is an Indus Valley urban Centre which lies on river Ravi ,city was supported by extensive agricultural production,Commerce and trade in summer in Southern Mesopotamia.(modern Iraq)

               Granaries at Harappa located outside the Citadel. Harappa too  follows a plan of a small high Citadel to the west and a lower City to the east. Streets are arranged in a grid pattern.it was the first Indus Valley site to be excavated by a Dayaram Sahni in 1921.

Kalibangan

           It is situated on the Southern bank of the Ghaggar river in Ganga nagar district of Rajasthan. 

          BP Lal and BK Thapper led the excavation of Kalibangan in 1961 to1969.full  it has witnessed both pre Harappan and Harappan cultural phases. 

 Excavations have revealed the evidence of plough fields, knowledge of copper technology and rich remains of earthen and vessels.

             Evidence of a platform with a well and a rectangular pit,brick  fire altar containing bones of cattle and deer indicating animal sacrifices. kalibangan name translated to black bangle. a fire altar was discovered here. 

Dholavira.

              It is located on the  Khadir bet island in the Kutch desert wildlife sanctuary in the Great Rann of Kutch.Dholavira was first noticed byJP Joshi but extensive excavation was conducted by RS Bisht iis in 1990 to 1991. Dholavira was an important centre of trade between settlements in South Gujarat ,Sindh Punjab and Western Asia.

Lothal.

           It is on the top of Gulf of Cambay in Gujarat near Sabarmati river and the Arabian Sea. A bead factory and the Mesopotamian seal found here. 65 Terracotta sealing with Impressions of needed fibre ,matting and twisted cords were found here. The most distinctive feature of Lothal was the artificial dockyard which lies on the eastern end of the site.

Rakhigarhi 

               Rakhigarhi was one of the most prominent sides of Harappan Civilization.complete skeleton remains of a young male and female have been discovered from Rakhigarhi.

Both the early and mature Harappan Civilization have been found at Rakhi gaddi Rakhi gadi is the largest Harappan site in India and second largest after Mohenjo Daro in Indian subcontinent.

Ganeriwala

                 It is situated in Punjab (Pakistan )near Indian border, near a dry bed of Ghaggar or Saraswati river and has not been excavated yet .

Chanhudaro

                  It is situated in Sindh about 130 km south of Mohenjo-daro.

Chakunda was clearly an important centre of craft activity. Some of the houses yielded raw materials such as carnelian,agate,crystal as well as finished and unfinished beads and drills.

The most striking was the discovery of a bead factory. it was the only Indus city without a Citadel 

 .Banawali 

           In Hisar district (Haryana) which is on the bank of Rangoli river is a fortified site witnessed early, mature and late Harappan phases. Several houses at Banawali gave evidence of a fire altars in one place. These altars Were  associated with animal sacrifices.evidence of proto Harappan and Harappan cultural phases is found here.

Surkotada

             Surkotada is a small site in the state of Gujarat. It is the only side of Harappan Civilization where  remains of the horse are found.

Settlement pattern of Indus Valley Civilization.

 The most wonderful aspect of Indus valley civilization was the excellent town planning. The Indus valley civilization was an urban civilization.

town planning. 

• Its towns were divided into two parts ,the upper Parts or the Citadel and the lower part. Harappa and Mohenjo-daro both had their own citadel which was possibly occupied by the members of the ruling class. Below the Citadel in each city, lay a lower town containing a brickhouse, possibly inhabited by the common people. Dholavira is divided into three parts i.e Citadel, lower town and castle.

• Drainage system was one of the most remarkable features of Indus Valley Civilization. In its drainage system ,each house had its own drainage and soak pit which was connected to the public drainage. They were covered and had manholes at intervals for cleaning and clearing purposes. No other contemporary civilization gives so much attention to cleanliness.

• The streets :streets were straight and caught each other at right angles. They divided the city into rectangular blocks.

• The Buildings were of two stories, some even three. Houses were built in one line and roads and lanes cover the space between houses. Most houses had a well and a bathroom.

• Great bath :Great bath was another striking feature of Indus valley civilization, is the great bath ,in Mohenjo Daro. It consists of a huge swimming pool in the centre with the remains of galleries and rooms on all four sides. It has flight  of steps at either end and is fed by a well ,situated in one of the adjoining rooms. The tank was watertight with a thick layer of bitumen. There were arrangements for hot water both also in some rooms. The dimension of the great bath was 4.5 × 7 m ,with a maximum depth of 2.4 m.

• Granaries . It was a massive structure used to store the grains safely which were probably collected as a revenue or store houses to be used in emergencies.

• The great granary. The great granary was found at Mound at Harappa. It was a massive brick structure measuring 45m north south and 45 m east west.

Social life in Indus valley civilization.

                 The ruins and several evidence of Harappa and Mohenjo-daro reveal a great deal about the social life of people of Indus valley civilization.

It is not proved,whether there existed any classes or cast. But based upon the mounds, it can be assumed that there did exist classes ,based on the occupation of the people like craftsmen, artisans, herdsmen etc.

                Dominance of the mother goddess suggests that the family was a circle in nature.

Clothing.

              Cotton and wools were used as garments. Women wore skirts with a cloak as an extra covered protection, covering arms and shoulders.  Mens wore a piece of cloth around their loins and a wrapper covering their shoulder.

Household articles

            The kitchen utensils, vessels,fishers,jars were made up of soil and stone ,were found in Harappan sites.chairs and tables were used for decorating rooms and for sitting comfortably .goblets ,basins ,pans,saucers, storage and drinking vessels made up pottery, lamps made of copper ,shell  and clay were also found. Characteristic pottery painted red or black of various shapes and sizes.

Ornaments 

             men and women both found ornaments made of gold ,silver ,copper decorated with precious stones like jade,carnelian,agate  and lapis lazuli.

Seals, script and language. 

            Majority of historians believe that Harappan script is pictographic and alphabetic. On the other hand Natwar jha believes that the script was a syllabic system.

 Language of a script is also debated among historians where some believe that it is to be indo-european while others consider it to be indo-aryan or dravidian family.

Language and script 

            The language or languages of harappans are still unknown ,and most remain, so until the Harappan script is deciphered.broadly there would appear to be 2 main  contestants as to the nature of language that is belonged. however improbable to the indo-europeans or even indo-aryan family or that it belongs to the dravidian family. 

             In spite of careful analysis of the purpose of Harappan inscription now in the reason of 3,000,the task for decipherment  remains problematic and shortness of the inscription ,nearly all on seals or amulet tablets, renders it difficult to interpret.

Burial practices

                  Burial practices was also another striking feature of Indus Valley Civilization. Three form of burials have been found in Indus Valley Civilization i.e complete burials,functional burials and post- cremation burials.complete burial means burials of the whole body,ceremonially performed in various forms.fractional burial and post cremation Borealis complete details completed means budiyal of the whole body ceremonial perform in various forms along with Grave furniture and offering extra. Fractional burial 

             Fractional burial represents a collection of bones after the exposure of the body to wild beasts and birds.

               

               Post cremation  burial post cremation burial post have been inferred from large wide mouth urns  containing a number of smaller vessels bones of animals like the Lambs goats etc and of birds or fishes and variety of small objects such as beads, bangles figurines etc.At kalibangan thee type of burials have been identified.

At Lothal two types of burials practice were  followed.while one type contained,besides the grave goods ,a single skeleton,and other contained two skeletons buried together.

Economy of Indus Valley Civilization.

External trade (Persian Gulf and mesopotamia)

           External trade evidence shows Harappan participated in a vast Maritime sea trade network extending from Central Asia to the Middle East. This civilization's economy appears to have depended significantly on trade which was facilitated by major advances in transport Technology. 

          The Harappan Civilization were the first to use wheeled  transport,in the form of oxcart that are identical to those seen throughout South Asia today. 

          It also appears they  built boats and watercraft, a claim supported by archaeological discoveries of a massive,dredged  canal,and what is regarded as the Docking facility at the coastal city of Lothal.

 

            Harappans  also engaged in shell working and shell used in their crafts  have Origins from as far away as the coast of modern-day Oman. 

             Trade focused on important raw materials to be used in Harappan city workshops, including minerals from Iran and Afghanistan, lead and copper from other parts of India,jade  from China and Cedar wood floated down rivers from Himalaya and Kashmir. Other trade goods included Terracotta pots, gold ,silver, metal ,beads , flints  for making tools ,seashells ,pearls and colour gemstones such as lapis lazuli  and Turquoise.

 

              One of the ways historians know about the maritime trade network operating between the Harappans and Mesopotamia civilization,is the discovery of Harappan seals and jewellery at archaeological sites in the region of Mesopotamia, which includes most of modern day Iraq, Kuwait,and parts of Syria.

.

                 Long distance sea trade over bodies of water such as the Arabian Sea,red sea  and Persian Gulf may have also become feasible with the development of plank watercrafts. 

 Internal trade

 Internal trade is essential for sustenance of livelihoods and blossoming of economy.

• Knowledge of wheel and use of bullock cart which show movement of people and goods.

•  Granaries which were used to store grains were traded in the market.

• seals or different kinds of seals which were used as currency. Even the coinage system is supposed to exist. 

• Use of varied weighing instruments. 

• People in Indus/ Harappan Civilization used to trade in stones,minerals ,textile ,etc which were made from raw materials purchased from other towns.

•  the existence of an artificial Dockyard at Lothal.

Hence we can say that internal trade forest during Indus Harappan civilization.

Other important aspect of economy 

Transport 

              Bullock carts,pack oxen were employed for land transport ,for sea and river transport ships and boats were used. There is evidence of a Dockyard at Lothal.

An extensive canal  network used for irrigation was discovered by HP Frankfurt. 

Agriculture

                comparatively rainless,the indus region is not so fertile today,but  the prosperous villages and towns of the past testify that it was fertile  in ancient times. today the rainfall is about 15 CM but in the 4th century BC One of the historians of  Alexander informed us that Sindh was a fertile part of India.  In earlier times, the Indus region had more natural vegetation which contributed to rainfall. It is supplied with timber for baking bricks and also for construction. In course of time ,the natural vegetation was destroyed by the extension of agriculture, large-scale grazing and supply of fuel. The Harappan villagers mostly situated near the floodplains produced sufficient food grains not only for their inhabitants but also the townspeople. They must have worked Very hard to meet their own requirements as well as those of artisans,merchants and others who lived in this city and were not directly concerned with food production activities.

  

                  Indus people produced wheat, barley,Rai,peas,and the like. two types of wheat and barley were grown.A substantial quantity of Barley was discovered at Banawali. in addition , sesamum, mustard  were grown. Food grains were stored in Huge granaries in both Mohenjo Daro and Harappa and possibly in kalibangan. in all probability cereals were  received as the taxes from peasants and stored in granaries for the payment of wages as well as for use during emergencies. This can be summarised from the analogy of Mesopotamian cities where wages were paid in Barely. The Indus people were the earliest people to produce cotton.

Domestication of animals 

            Although the harappans practised agriculture, animals were raised on a large scale .Oxen, buffaloes ,goats ,sheep and pig were domesticated.Humped bull were favoured by harappans. There is evidence of dogs and cats from the outsets and assess and camels were bred and were obviously used as the beast of burden.The remains of horses are reported from surkotada,situated in West Gujarat.

Weight and Measurement

              The weight and Measurement were calibrated to a considerable extent. The measures we use are standardized and perhaps there is a Binary System in use. 

Other occupations 

            There were carpenters,goldsmith,Jewellers makers, stonecutter,blacksmith , weaver and potters.

Religion in Indus valley civilization. 

              No definite opinion about religion of Indus people. Ruins do not show any sign of temples and none of the buildings that have been discovered can be taken as houses for worship.But according to pictures in seals and earthen vessels the number for Goddesses were more than that of Gods suggested that they were mother worshippers. 

               They also worship trees ,stones ,animals and birds.They worshipped the linga and yoni symbols.stop loss if the Ling and Yoni symbol people had faith in animals and charms shows that they were afraid of Demons. They also practiced yoga. 

Female figurines. 

              Most striking and extremely common are female figurines in Terracotta. Similar figurines have also been found in large numbers from Iran ,Mesopotamia, Asia Minor ,Syria ,Palestine ,Cypress ,the Balkan and Egypt.

 Presence of fertility culture is also represented by figurines of pregnant women and of women with children. A common fig rain female wearing a loincloth with or without a griddle, a lot of jewelry and a fan-shaped dress with two cup-like objects near the ears.

 Male divinities. 

              Male divinities characterized by a horned headdress, which symbolised supernatural power. A three faced God wearing a pair of horns in the form of Trident with lots of jewellery. John Marshall suggested that these mail deities represented a prototype of the historic Lord Shiva in his Pashupati aspect.

Trees and animals

               Trees and animals for seed seem to have been found a place very early in the life of Indus people earliest representation occurs in the form of a Peepal leaf which symbolises the tree.motifs and  incense burner have been found on seals.

Animals depicted on seales are the bison, the Bison,the tigers, rhinoceros, elephant and buffalo. 

Polity 

             Harappan culture is more or less uniform over a large area, central authority may have contributed to this.we may identify some important elements of the state in the Indus valley. The Arthashastra of Kautilya considers sovereignty ,ministers polluted territory ,forts,Treasury ,force and friends to the organ of the state. in the Harappan culture the Citadel may have been the seat of sovereign power,the Middletown may have been the area where bureaucrats lived for the seat of Government and the great granary at Mohenjo Daro may have been the treasury.it appears that taxes were collected in grain.also, the entire Harappan area was a well populated territory.fortification was a feature of several cities .Dholavira, in particular,had  forts within forts.We have  no clear idea of an organised force or standing Army but a heap of sling stones and the depiction of a soldier on a post at surkotada may suggest a standing army

Decline of Indus Valley Civilization.

        The reason for decline of Indus Valley Civilization has been widely debated among  historians.They have put  various theories for the decline of Civilization which include the following. 

Aryan invasion 

• According to some scholars, Aryan invaded and conquered the Indus valley civilization,though more recent evidence tends to contradict this claim. Stuart , Piggott and Garson Childe believe that  Aryan invasion Surat I got and Gordon childe believe was the main reason for the decline of the civilization which led to slow amalgamation  of the two cultures. 

Floods

•  Some historians believe that drying of Saraswati river which began around 1900 BCE  ,was the main cause for climate change, while other scholars conclude  that great floods  struck the area.

 Tectonic disturbances. 

• According to some scholars tectonic disturbances were the main reason for the decline. 

Deforestation. 

• Some historians have the statement that deforestation ultimately affected  the agricultural economy.scarcity of resources and ecological imbalance resulted in the decline.

Change of course of river ghaggar

• . Many scholars argue that changes in rever patterns cause the large civilization to break up into smaller communities called late Harappan culture . 

Epidemic

• KVR Kennedy is one of the opinion that the epidemic was the main reason for the decline of Indus Valley Civilization .

INUNDATION

• MR Sahni is of the opinion that Inundation Was the main reason for the decline. 

Large scale destruction 

• Wheeler believes that large scale destruction was one of the major reasons for decline of Indus Valley Civilization. 

Change of climate

•  eastward moving monsoon winds that bring heavy rains in Indus valley Civilization.. Monsoon can be both helpful and detrimental to the climate depending on whether they support or destroy vegetation and Agriculture . 

• By 1800BCE bad climatic conditions and tectonic events may have diverted or disrupted the river systems ,which were the lifelines of the Indus valley civilization.

• Migration of Harappan communities towards Ganga basin in the east and established settle villages..

• These small communities  would not have been able to produce the same agricultural surplus to support large cities.

With reduced production of goods ,there would have been a decline in trade with Egypt and Mesopotamia. By around 1700BC,most of the Indus civilization had been abandoned.