The demographic make-up of the population of the ice age Indus Valley Civilization (of several million people) is revealed in the name of the submerged city of Kushasthali in the gulf of Kutch, those people of dark skin, progeny of Kush (by his sons Seba/Shiva and Ramah) who quickly adopted Indo European language (japhetic) proven by the thali in Kushasthali, like the Greek word thalassic, of the sea.
