The Aksumites were a people formed from the mix of Kushitic speaking people in Ethiopia and Semitic speaking people in southern Arabia who settled the territory across the Red Sea around 500 BC. The Aksumites lived in the Ethiopian highlands near the Red Sea, and so enjoyed a strategic position in the trade routes between Yemen (in the south of the Arabian peninsula) and the cities of Nubia. They spoke a strongly Semitic language and wrote in Semitic characters; Ethiopia, in fact, has one of the longest continuous literate traditions in Africa.
We know very little about the early Axumite kingdom. Roman and Greek sources indicate that an Axumite kingdom was thriving in the first century AD; the city of Adulis is frequently mentioned because it had become one of the most important port cities in Africa.
Aksum lay dead in the path of the growing commercial trade routes between Africa, Arabia, and India. As a result, it became fabulously wealthy and its major cities, Adulis, Aksum, and Matara, became three of the most important cosmopolitan centers in the ancient world. Although they were off the beaten path as far as European history is concerned, they were just as cosmopolitan and culturally important in that they served as a crossroads to a variety of cultures: Egyptian, Sudanic, Arabic, Middle Eastern, and Indian. Perhaps an indication of this cosmopolitan character can be found in the fact that the major Aksumite cities had Jewish, Nubian, Christian, and even Buddhist minorities.
In the second century AD, Aksum acquired tribute states on the Arabian Peninsula across the Red Sea, conquered northern Ethiopia, and then finally conquered Kush. The downfall of the Nubian powers led to the meteoric rise of Aksumite imperial power. The Aksumites controlled one of the most important trade routes in the world and occupied one of the most fertile regions in the world.
The Aksumite religion was actually derived from Arabic religion. It was a polytheistic religion which believed that the gods controlled the natural forces of the universe. However, in the fourth century, Ezana, who was a folllower of Axumite religion, converted to Christianity under the tutelage of a Syrian bishop named Frumentius. Ezana declared Axum to be a Christian state , thus making it the first Christian state in the history of the world, and began actively converting the population to Christianity.
Ethiopian Christianity was slightly different from its Greek origins. Under the influence of Egyptian Christians, the Axumites believed that Christ had a single rather than a double nature (man and god): this is called Monophysite (mono=single, physis=nature) Christianity and was considered heretical in the European churches. In the fifth century AD, the Axumites replaced Greek in the liturgy and began using their own native language, Ge'ez. Finally, because of their Semitic origins, the Ethiopians believed that they were descendants of the Hebrews, who were also Semitic. They traced their origins all the way back to David. So the Ethiopians, unlike other Christians, really saw themselves as inheriting the covenants that Yahweh entered into with his chosen people (as a side note, the Ethiopic Church claims to have the Ark of the Covenant which is the chest in which the Decalogue was kept by the Hebrews).
Axum remained a strong empire and trading power until the rise of Islam in the seventh century AD. However, because the Axumites had sheltered Muhammed's first followers, the Muslims never attempted to overthrow Axum as they spread across the face of Africa. Even though Axum no longer served as a center or hub of international trade, it nonetheless enjoyed good relations with all of its Muslim neighbors. Two Christian states north of Axum, Maqurra and Alwa, survived until the thirteenth century when they were finally forced by Muslim migration to become Islamic. Axum, however, remained untouched by the Islamic movements across Africa. Because of this, the Ethiopic (or Abyssinian) Church has lasted until the present day. It is still a Monophysite church and its scriptures and liturgy are still in Ge'ez.