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India

One of the earliest Neolithic sites in the Indian subcontinent is Bhirrana along the ancient Ghaggar-Hakra riverine system in the present day state of Haryana in India, dating to around 7600 BC. Other early sites include Lahuradewa in the Middle Ganges region and Jhusi near the confluence of Ganges and Yamuna rivers, both dating to around 7000 BC.

The aceramic Neolithic at Mehrgarh in present-day Pakistan lasts from 7000 to 5500 BC, with the ceramic Neolithic at Mehrgarh lasting up to 3300 BC; blending into the Early Bronze Age. Mehrgarh is one of the earliest sites with evidence of farming and herding in the Indian subcontinent. It is likely that the culture centered around Mehrgarh migrated into the Indus Valley in present-day Pakistan and became the Indus Valley Civilisation. The earliest fortified town in the region is found at Rehman Dheri, dated 4000 BC in Khyber Pakhtunkhwa close to River Zhob Valley in present-day Pakistan. Other fortified towns found to date are at Amri (3600–3300 BC), Kot Diji in Sindh, and at Kalibangan (3000 BC) at the Hakra River.

The Indus Valley Civilization starts around 3300 BC with what is referred to as the Early Harappan Phase (3300–2600 BC), although at the start this was still a village-based culture, leaving mostly pottery for archaeologists. The earliest examples of the Indus script date to this period, as well as the emergence of citadels representing centralised authority and an increasingly urban quality of life. Trade networks linked this culture with related regional cultures and distant sources of raw materials, including lapis lazuli and other materials for bead-making. By around 2600 BC, villagers had domesticated numerous crops, including peas, sesame seeds, dates, and cotton, as well as animals, including the water buffalo.

2600 to 1900 BC marks the Mature Harappan Phase during which Early Harappan communities turned into large urban centers including Harappa, Dholavira, Mohenjo-Daro, Lothal, Rupar, and Rakhigarhi, and more than 1,000 towns and villages, often of relatively small size. Mature Harappans evolved new techniques in metallurgy and produced copper, bronze, lead, and tin and displayed advanced levels of engineering. As seen in Harappa, Mohenjo-daro and the recently partially excavated Rakhigarhi, this urban plan included the world's first known urban sanitation systems: see hydraulic engineering of the Indus Valley civilization. Within the city, individual homes or groups of homes obtained water from wells. From a room that appears to have been set aside for bathing, waste water was directed to covered drains, which lined the major streets. Houses opened only to inner courtyards and smaller lanes. The housebuilding in some villages in the region still resembles in some respects the housebuilding of the Harappans. The advanced architecture of the Harappans is shown by their impressive dockyards, granaries, warehouses, brick platforms, and protective walls. The massive walls of Indus cities most likely protected the Harappans from floods and may have dissuaded military conflicts.

The people of the Indus Civilization achieved great accuracy in measuring length, mass, and time. They were among the first to develop a system of uniform weights and measures. A comparison of available objects indicates large scale variation across the Indus territories. Their smallest division, which is marked on an ivory scale found in Lothal in Gujarat, was approximately 1.704 mm, the smallest division ever recorded on a scale of the Bronze Age. Harappan engineers followed the decimal division of measurement for all practical purposes, including the measurement of mass as revealed by their hexahedron weights. These chert weights were in a ratio of 5:2:1 with weights of 0.05, 0.1, 0.2, 0.5, 1, 2, 5, 10, 20, 50, 100, 200, and 500 units, with each unit weighing approximately 28 grams, similar to the English Imperial ounce or Greek uncia, and smaller objects were weighed in similar ratios with the units of 0.871. However, as in other cultures, actual weights were not uniform throughout the area. The weights and measures later used in Kautilya 's Arthashastra (4th century BC) are the same as those used in Lothal.

Around 1800 BC, signs of a gradual decline began to emerge, and by around 1700 BC most of the cities had been abandoned. Suggested contributory causes for the localisation of the IVC include changes in the course of the river, and climate change that is also signalled for the neighbouring areas of the Middle East. As of 2016 many scholars believe that drought led to a decline in trade with Egypt and Mesopotamia contributing to the collapse of the Indus Civilization. The Ghaggar-Hakra system was rain-fed, and water-supply depended on the monsoons. The Indus Valley climate grew significantly cooler and drier from about 1800 BC, linked to a general weakening of the monsoon at that time. The Indian monsoon declined and aridity increased, with the Ghaggar-Hakra retracting its reach towards the foothills of the Himalaya, leading to erratic and less extensive floods that made inundation agriculture less sustainable. Aridification reduced the water supply enough to cause the civilization's demise, and to scatter its population eastward. As the monsoons kept shifting south, the floods grew too erratic for sustainable agricultural activities. The residents then migrated away into smaller communities. However trade with the old cities did not flourish. The small surplus produced in these small communities did not allow development of trade, and the cities died out. The Indo-Aryan people migrated into the Indus River Valley during this period and began the Vedic age of India. The Indus Valley Civilization did not disappear suddenly and many elements of the civilization continued in later Indian subcontinent and Vedic cultures.