How did the arrival of Europeans and other foreign cultures affect the East African coast, and how did Ethiopia and the Swahili city-states respond to these incursions?

East Africa in the early modern period faced repeated incursions from foreign powers. At the beginning of the sixteenth century Ethiopia faced challenges from the Muslim state of Adal, and then from Europeans. Jesuit attempts to substitute Roman Catholic liturgical forms for the Coptic Christian liturgies (see below) met with fierce resistance and ushered in a centuries-long period of hostility to foreigners. The wealthy Swahili city-states along the southeastern African coast also resisted European intrusions in the sixteenth century, with even more disastrous results. Cities such as Mogadishu, Kilwa, and Sofala used Arabic as the language of communication, and their commercial economies had long been tied to the trade of the Indian Ocean. The arrival of the Portuguese in 1498 proved catastrophic for those cities, and the Swahili coast suffered economic decline as a result.