5.2 First civilisation
Archaeology shows that modern humans have been present in the subcontinent for at least thirty thousand years. It does not show by what route they arrived, but if they came from Africa it stands to reason that they would have entered from the northwest. Genetic evidence provides some support for this inference. It points to an early human expansion from the Horn of Africa along the southern coast of Eurasia, starting with Arabia and continuing to India and beyond. There is more direct evidence for the route by which farming first entered India. Domesticated crops appear by around 6000 B.C. in the extreme northwest of the subcontinent, and only later are they found in the rest of India, reaching the south by the third millennium B.C. Toward the middle of the same millennium the Indus Valley civilization emerged. It is unlikely to have been an accident that this first Indian civilization took shape in the part of India that was closest to Mesopotamia and most similar to it-and never spread to the rest of the subcontinent.
Far less is known about the Indus Valley civilization than about that of Mesopotamia. We have no idea what the people in question called themselves, or what kind of language they spoke; for convenience we often refer to them as Harappans, from the name of a major archaeological site that was once one of their cities. They had unusually regular town planning but there is no evidence for the political structures that made this possible. There are two main reasons why our knowledge is so limited. We have considerable numbers of inscribed stone seals; but the inscriptions are short, and cannot be deciphered. In marked contrast to the Near East, this region has left us no clay tablets or long inscriptions on stone. The obvious assumption is that the Harappans did most of their writing on perishable materials; if later Indian practice is anything to go by, they may have used palm leaves.
The second reason for our ignorance is that their civilization came to an end early in the second millennium B.C. The cause could have been environmental (for one thing, the Indus is a notably unstable river); or it could have been invasion. Therefore later Indian tradition retains no memory of the Indus Valley civilization. This does not mean that the Harappans contributed nothing to the India of later times; some features of their culture do not go away, including perhaps a liking for the number sixteen manifested in their system of weights. But there is no equivalent to the historical information that the Chinese tradition preserves on the Shang dynasty. The other consequence of the early end of the civilization is that no outsiders have left us any account of it.