A major empire of the ancient world, the kingdom of Aksum arose in Ethiopia during the first century C.E. This wealthy African civilization thrived for centuries, controlling a large territorial state and access to vast trade routes linking the Roman Empire to the Middle East and India. Aksum, the capital city, was a metropolis with a peak population as high as 20,000. Aksum was also noteworthy for its elaborate monuments and written script, as well as for introducing the Christian religion to the rest of sub-Saharan Africa.
I kinda just copied from national geography, hope it helps you:)