According to R.E.M. Wheeler, what is mentioned in the Rigveda related to Mohenjodaro's archaeological evidence?

References to fortified citadels

Deadman Lane, a narrow alley ranging from 3 to 6 feet in width, acquired its name due to the discovery of human remains in the area. Part of an adult skull, bones of the thorax and upper arm, and fragments of a tiny skull were found in fragile condition at a depth of 4 ft 2 in. The body was positioned diagonally across the lane. In 1925, sixteen skeletons were unearthed in the same vicinity, still adorned with their ornaments at the time of their death.

In 1947, R.E.M. Wheeler, the Director-General of the ASI (Archaeological Survey of India), attempted to connect this archaeological evidence with the Rigveda, the oldest known text in the subcontinent. He suggested that the Rigveda's mention of "pur," meaning rampart, fort, or stronghold, and the reference to Indra as the "fort-destroyer" might align with the fortified structures discovered in Harappa. Wheeler proposed that deliberate and large-scale destruction, potentially related to a massacre, led to the ultimate demise of the Harappan civilization.