How did the expansion of islam affect african societies

The expansion of Islam along the eastern coast of Africa happened between the 8th and 9th centuries when travelers, Arab traders and clerigs began to spread the religion. The presence of Muslim merchants stimulated the development of urban communities; mosques were built and a Sudano-Sahelian building style was adopted. The expansion of Islam was good for African societies since it brought new techniques of weighting and the art of writing to Africa.