Considering the global transmission of religious ideas through modern communications and that millions of Muslims reside in predominantly non-Muslim countries, Islam, in a sense, has spread around the world. If, however, “spread” refers only to those regions where most of the inhabitants embrace Islam, then Islam has spread mainly over an expanse stretching roughly from the west coast of Africa to Indonesia, approximately between five degrees south of the Equator and 45 degrees north.

Arab Conquests

As early as 629, three years before the death of Muhammad, the prophet’s Arab followers launched an incursion into the region directly to the northwest of the Arabian Peninsula, notes “The Cambridge Illustrated History of the Islamic World.” By 750, Muslim armies had spread Islam through Egypt across North Africa and into Spain, encompassing most of the Iberian Peninsula, observes Professor Hugh Kennedy in his book “The Great Arab Conquests.” During the same period, Muslim armies spread their faith to the north and east of the Arabian Peninsula as far as the Indus River, across territory that would belong to the 20th-century states of Iraq, Iran and Afghanistan.

Turkic Conquests

By the end of the 11th century, governance of the Islamic world had passed mainly from Arab to Turkic groups, according to “The Cambridge Illustrated History of the Islamic World.” The Ottoman Turks spread Islam through the territorial remnants of the Byzantine Empire including, in 1453, Constantinople and, later, much of southeastern Europe. Between 1525 and 1707, the Timurid Mughals, a Turkic-Mongol group, spread Islam through most of the Indian subcontinent while, during approximately the same period, the Muslim Uzbeks, a Turkic group, spread Islam from northwestern China eastward to the environs of Crimea and as far north as the city of Kazan, future capital of the Russian republic of Tatarstan.

Sub-Saharan Africa

Carried by Muslim merchants, religious teachers and holy men, as well as by its armies, Islam in Africa, by the end of the 16th century, was spreading south of the Sahara Desert, notes “The Cambridge Illustrated History of the Islamic World.” By 1700, the faith had spread across the continent in a broad band from the Atlantic coast of West Africa to the Red Sea, south along most of Africa’s eastern coast and even beyond it, to the island of Madagascar.

East Asia

Arab traders were conducting business in East Asia even before the birth of Islam, according to the International World History Project. Once converted to Islam, they took their faith with them into Southeast Asia, to Malaya and the islands of Sumatra and Java. By 1565, when the Spanish arrived in the Philippines, the centuries-long presence of Muslims in commerce had helped to make many converts to Islam, encouraging and supporting the construction of Muslim states in the region, including in the Philippines, notes “The Cambridge Illustrated History of the Islamic World.”