Himyarite Kingdom
The Kingdom of Aksum (also known as the Aksumite Empire) was an ancient state located in the Eritrea and Ethiopian highlands, which thrived between the 1st and 7th centuries AD. A major player in the commerce between the Roman Empire and Ancient India, Aksum's rulers facilitated trade by minting their own currency. The state also established its hegemony over the declining Kingdom of Kush and regularly entered the politics of the kingdoms on the Arabian peninsula, eventually extending its rule over the region with the conquest of the Himyarite Kingdom. Under Ezana (fl. 320–360), the kingdom of Aksum became the first major empire to adopt Christianity, and was named by Mani as one of the four great powers of his time, along with Persia, Rome and China.