Excerpts from Books and Wikipedia
Muawiya was governor of Syria when he rebelled against Caliph Ali in 657. He was angry that Caliph Ali did not punish the murderers of his cousin Caliph Uthman (644-656). The Umayyads ruled in the new capital at Damascus until 750, and Arabic became the language from Spain to central Asia. [Furtado: 1001 Days]