In 20 H / 641 CE, during the reign of Caliph Umar ibn al-Khattab, Muslim troops took over current Egypt and conquered current Libya the following year. Muslims then expanded to current Tunisia in 27 H / 647 CE, during the reign of the third Muslim Caliph Uthman Ibn Affan. The conquest of North Africa continued under the Umayyad dynasty, which annexed parts of Algeria around 61 H/680 CE and Morocco the following year. From the latter Muslim troops crossed the Strait of Gibraltar to Europe in 92 H/711 CE. Islam gained momentum during the 10th century in West Africa with the start of the Almoravid dynasty movement on the Senegal River and as rulers and kings embraced Islam. Islam then spread slowly in much of the continent through trade and preaching. During this period these Muslims from North and West Africa came to be known by Europeans at large as Moors . By the 9th century, Muslim Sultanates started being established in the Horn of Africa, and by the 12th century, the Kilwa Sultanate had spread as far south as Mozambique. Islam only crossed deeper into Malawi and Congo in the second half of the 19th century under the Zanzibar Sultanate. Then the British brought their labor force from India, including some Muslim-Indian nationals, to their colonies in Africa towards the end of the nineteenth and beginning of the twentieth century.