When I went to Gujrat many years ago I visited Somnath. There I met some Siddhis, the African Indians, whose ancestors came to India, probably as slaves centuries ago ( in Pakistan they are known as 'Sheedis' ). They are mostly Muslims, and speak Gujrati, but have retained some of their African culture. Some also live in Karnataka.
While the ancestors of blacks in America were brought from Western Africa, the blacks in Asia were probably brought from Zanzibar ( which is an island, now part of Tanzania ), in Eastern Africa.
I visited Zanzibar some years ago. It was once under the Sultans of Oman. There was once a large slave market in Zanzibar. Africans from the mainland were captured and brought there to be sold as slaves in several countries. I visited the place which was the slave market, and has been preserved, It was a horrible, dingy and gloomy place, where the captured Africans lived in terrible conditions.
We have several accounts of Africans living in India in our history. Razia Sultan had fallen in love with Yaqut, a black man, which was said to be the cause of her downfall. In the Mutiny of 1857, 'Bob the Nailer', was said to be a black who 'nailed' every defender of the Residency in Lucknow with just one shot.
Today these African Indians live in poverty, mostly as labourers. Our government should do everything to uplift their social conditions, and thus undo the great historical wrong done to them