Indians like to claim credit for all and sundry where credit is not due.
Like Buddhism.
Here is wiki written by Indians.
https://en.wikipedia.org/wiki/Shakya
The Shakya (Sakya and Sakiya[1][2][3]) were a clan of the late Vedic period (1000-500 BCE).
The best-known Shakya was Siddhartha Gautama Shakya, who was the founder of Buddhism (c. 6th to 4th centuries BCE) and came to be known as Gautama Buddha
Annexation by Kosala
Virudhaka, as an act of vengeance, he invaded the Shakya territory,
massacred them and annexed it.
Religion
It is uncertain whether, by the time of Siddhartha's birth, Vedic Brahmanism had been adopted to any significant extent by the Shakyans.
However, the bearers of this tradition, the Brahmins, did not occupy a dominant position in the area in which the Buddha preached his message.
How could Buddhism be from India when the Buddha's people are massacred by them.
More probably survivors of the massacre escaped to Tibet, Myanmar and Thailand.
The Indians themselves state,
Brahmins are not dominant in areas the Buddha preach.
So who are the people living in the Buddha's time in the area around ancient Nepal before they are massacred into oblivion.
Most probably East Asians or Tibeto-Burman.
.