The Eritrean-Ethiopian region has been exposed to population movements and migrations from northern Africa, across the Red Sea, and from the south. Eritrea History and Culture Information and Travel Guide. Vacation package Book. On the border between Eritrea and Ethiopia, one also finds traces of some of Africa's oldest civilizations. The Axumite empire, which emerges into the light of history in the first century C.E. , comprised the Akkele-Guzai region of highland Eritrea and the Agame region of Tigray, Ethiopia. The empire expanded and its port city of Adulis, south of present-day Massawa, became an important trading post hosting ships from Egypt, Greece, the Arab world, and other far-off areas. In the early fourth century Enzana, the king of Axum, converted to Christianity. He thus established Christianity as the religion of the court and state, making the Ethiopian/Eritrean Christian Church one of the oldest in the world. The decline of the Axumite empire began around 800, when its area of dominance became too big to administer efficiently. Moreover, local resistance and uprisings coupled with the domination of overseas trade by the Islamic empire in the Middle East led to the collapse of the kingdom. Ethiopia was subsequently constructed on the legacy of Axum