Historian Romila Thapar haș talked about Farrukhi Sistani’s claims in her 1999 essay, “Somnath and Mahmud.” Here’s an excerpt:
“According to [Farrukhi Sistani], the idol was not of a Hindu deity but of a pre-Islamic Arabian goddess. He tells us that the name Somnat (as it was often written in Persian) is actually Su-manat, the place of Manat. We know from the Qur'an that Lat, Uzza and Manat were the three pre-Islamic goddesses widely worshipped, and the destruction of their shrines and images, it was said, had been ordered by the Prophet Mohammad. Two were destroyed, but Manat was believed to have been secreted away to Gujarat and installed in a place of worship. According to some descriptions, Manat was an aniconic block of black stone, so the form could be similar to a lingam.”
The Arab civilization was polytheistic before the rise of Islam in the seventh century, and they had close connections with the Indian subcontinent. There is no record of the Arabs attacking any nation while they were polytheistic—they were very peaceful in their long polytheistic age.