The Umayyad Caliphate (Omayyad) was the second of the four major caliphates established after the death of Muhammad. The caliphate was ruled by the Umayyad dynasty, hailing from Mecca. Syria remained the Umayyads' main power base thereafter, and Damascus was their capital. The Umayyads continued the Muslim conquests, incorporating the Transoxiana, Sindh, the Maghreb and the Iberian Peninsula (Al-Andalus) into the Muslim world. At its greatest extent, the Umayyad Caliphate covered 4,300,000 square miles and 62 million people (29% of the world's population), making it one of the largest empires in history in both area and proportion of the world's population.