<P> 2600 BC marks the Mature Harappan Phase during which Early Harappan communities turned into large urban centres 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 Civilisation . 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 house - building in some villages in the region still resembles in some respects the house - building 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 . </P> <P> The people of the Indus Civilisation 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 . </P> <P> 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 lead to a decline in trade with Egypt and Mesopotamia contributing to the collapse of the Indus Civilisation . 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 civilisation'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 towards the Ganges basin in the east, where they established smaller villages and isolated farms . 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 peoples migrated into the Indus River Valley during this period and began the Vedic age of India . The Indus Valley Civilisation did not disappear suddenly and many elements of the civilization continued in later Indian subcontinent and Vedic cultures . </P> <P> Early evidence for Chinese millet agriculture is dated to around 7000 BC, with the earliest evidence of cultivated rice found at Chengtoushan near the Yangtze River, dated to 6500 BC . Chengtoushan may also be the site of the first walled city in China . This Neolithic Revolution gave rise to the Jiahu culture (7000 to 5800 BC). Some scholars have suggested that the Jiahu symbols (6600 BC) are the earliest form of proto - writing in China . However, it is likely that they should not be understood as writing itself, but as features of a lengthy period of sign - use which led eventually to a fully - fledged system of writing . Excavation of a Peiligang culture site in Xinzheng county, Henan, found a community that flourished in 5500 to 4900 BC, with evidence of agriculture, constructed buildings, pottery, and burial of the dead . With agriculture came increased population, the ability to store and redistribute crops, and the potential to support specialist craftsmen and administrators . In late Neolithic times, the Yellow River valley began to establish itself as a center of Yangshao culture (5000 to 3000 BC), and the first villages were founded . Later, Yangshao culture was superseded by the Longshan culture, which was also centered on the Yellow River from about 3000 to 2000 BC . The earliest bronze artifacts have been found in the Majiayao culture site (3100 to 2700 BC). </P>

Chinese civilization occurred independently about the same time as greek civilization arose