Aksum became a major player on the commercial route between the Roman Empire and Ancient India. The Aksumite rulers made trade easier by minting their own Aksumite currency. The state also assumed its hegemony over the declining Kingdom of Kush. It also regularly entered the politics of the kingdoms on the Arabian Peninsula and eventually extended its rule over the region with the conquest of the Himyarite Kingdom. The Manichaei prophet Mani (died 274 AD) regarded Axum as one of the four great powers of his time; the others were Persia, Rome, and China. 