The round temple of farthest China

The Round Temple of China is a shrine at the far reaches of China, described by al-Mas'udi. It has seven doors, and inside it is a seven-sided dome. ²

At the top of the dome is something like a jewel, from which light shines across the sides of the temple. Al-Mas'udi says that a group of kings tried to take it, but no one could come within ten cubits of it without their instruments being reflected and disabled, and whoever tried to demolish the temple died. ²

According to al-Mas'udi, a group of experts hold that this is due to a repelling force from kinds of magnetic stone. ²

Inside the temple there is a well with a seven-sided mouth. On its rim is a collar inscribed in a script resembling musnad. The inscription says that it leads to a store of books, the history of the world, and the sciences of the heavens. ²

The whole report is transmitted from al-Mas'udi. An additional source is needed.