The two limits of the Indus civilization are now easy to assess, based on the first and last occurrences of Harappan objects in independently dated contexts in Mesopotamia. The first occurrence is in the form of two bead-types—etched carnelian and long barrel-cylinder types—in the Royal Graves at Ur. These graves belong to Early Dynastic III A context of Mesopotamia, i.e. c. 2600 BC. These two bead-types do not occur in early Harappan context in the subcontinent. Besides, there is no evidence whatsoever of contact between the Indus region and Mesopotamia in the early Harappan context. The fact that they occur in the context of c. 2600 BC in Mesopotamia shows that the Indus civilization had already come into existence; c. 2600 BC is thus the earliest, archaeologically proven limit. The last limit is shown by the occurrence of a square Indus seal with a bull and pictographs in the Kassite context of c. fourteenth century BC at the Mesopotamian site of Nippur. The fact that the Indus civilization was alive during this period is also proved by the occurrence of two round seals with the Indus script in the Kassite context at Failaka. The ‘fourteenth century BC’ means the range of 1400–1300 BC. We can say that the Indus civilization came into existence by c. 2600 BC and was alive at 1400 BC and later. This is the baseline; the exact points of the beginning and the end are difficult to determine and perhaps not even necessary. But one may safely accept the broad chronology of the Indus civilization in the subcontinent from c. 2700 BC to c. 1300 BC.
Many radiocarbon dates are now available from the mature Harappan contexts. Sites which have each yielded a large number of dates are Harappa, Kalibangan, Lothal, Surkotada, Rojdi and Shortughai. Dates have been obtained from many other sites as well, but in limited numbers. At this point one has to note that all these sites did not come into existence simultaneously; they have their own variations in time. Taking all the calibrated dates of this civilization, it becomes apparent that the earliest focus is around 2600 BC, with only a limited number of dates suggesting an earlier focus, say, up to 2700/2800 BC. The lowest limit is more difficult to determine. At Mohenjodaro it was on its way out by 2000 BC, but the late phase of the civilization continued at many sites (cf. Hulas, Bhagwanpura) till c. 1300 BC and still later.