It is true that the Rigveda does not provide us details of the inner layout of these forts, but surely the text was not meant to be a treatise on Vas… - B. B. Lal

Lal (1997, 9) considers the Sarasvati to have been alive in Kalibangan in the third millennium B.C.E. and dried up at the turn of the millennium: "The Sarasvati dried up around 2000 BC. This clearly establishes that the Rigveda, which speaks of the Sarasvati as a mighty flowing river, has to be assigned to a period prior to 2000 BC. By how many centuries it cannot be said for certain" (Lal, forthcoming).

At Ayodhya, as many as fourteen trenches were laid out at different spots, one of which was the area known as the Janmabhumi. Over here is a trench hardly three metres to the south of the compound wall of the structure known as Babri Masjid, a series of square brick-bases, running in parallel east-west and north-south rows, were discovered within about 25-30 cm. below the surface. Since one row of these pillar-bases lay under the edge of the trench towards the compound wall of the mosque, it is likely that there may exist many more such pillar-bases in the unexcavated area in that direction. Stratigraphic evidence indicates that these pillar-bases are ascribable to a period around A.D. 1100. From the level associated with the destruction of these pillar-bases has been found glazed pottery ascribable to fourteenth-fifteenth century A.D.

The obvious result [of the diversion of the Sarasvatī’s waters into the Yamuna system] was the migration of the [Harappan] people towards the north-east where some water was still available in the uppermost reaches of the Sarasvatī and Ghaggar and further east in the upper plains of the Gangā-Yamunā Doāb.’