Shiva, Varuna, Yama, Durga-Parvati, we already said it, are deities of IE origin, the rituals concerning fire, soma and the person of the king are eq… - Bernard Sergen

The Kurgan people had to originate in Central Asia.

Indeed, from the Indus eastwards, we lose track of this Bactrian invasion. Sergent himself admits as much: “For the sequel, archaeology offers little help. The diggings in India for the 2nd millennium BC reveal a large number of regional cultures, generally rather poor, and to decree what within them represents the Indo-Aryan or the indigenous contribution would be arbitrary. If Pirak (…) represents the start of Indian culture, there is in the present state of Indian archaeology no ‘post-Pirak’ except at Pirak itself, which lasted till the 7th century BC: the site remained, along with a few very nearby ones, isolated.” So, the Bactrian invaders who arrived through the Bolan pass and established themselves in and around the border town of Pirak, never crossed the Indus.

One of the paradoxes of India is its astonishing linguistic diversity (they speak about five hundred languages there) compared with its cultural unity.