The Mossi empire resisted both Islamization and foreign rule for over two centuries

Evidence

To the far north lay the great Mossi empire centered in Ouagadougou on the Upper Volta River, whose rulers, the Moro Nahas, had effectively resisted Islamicization and indeed any foreign penetration for more than two centuries. When they also refused French “protection” in the early 189o’s, the French decided in I896 to occupy Ouagadougou by force. — Alice L. Conklin, A Mission to Civilize_ The Republican…, 122