Muslim-Christian relations sour during the reign of the aggressive Negus Yeshaq (ruled 1414-29).

Forces of his rapidly expanding empire descend from Ethiopia's highlands to despoil Muslim settlements in the valley east of the ancient city of Harar.

Having branded the Muslims "enemies of the Lord," Yeshaq invades the Muslim kingdom of Ifat in 1415.

He crushes the armies of Ifat and puts to flight in the wastes along the Gulf of Tadjoura (in present- day Djibouti) Ifat's king Saa'd ad Din.

Yeshaq follows Sa'ad ad Din to the island off the coast of Zeila (which still bears his name), where the Muslim king is killed.

Yeshaq compels the Muslims to offer tribute, and also orders his singers to compose a gloating hymn of thanksgiving for his victory.

In the hymn's lyrics, the word Somali appears for the first time in written record.