Beginnings in 7th-century Arabia

Islam began in the early 7th century CE in the Arabian Peninsula, when the Prophet Muhammad ﷺ began calling people to the worship of the one God around 610 CE in Mecca.245 (For his life in detail, see The Life of the Prophet ﷺ.) Over roughly twenty-three years the message took shape as the Quran, and near the end of the Prophet's life the Quran described that message as complete:

"This day I have perfected for you your religion and completed My favor upon you and have approved for you Islam as religion."

— Quran 5:3 (Saheeh International)1

When the Prophet ﷺ died in 632 CE, Islam had united much of the Arabian Peninsula.

The Rightly-Guided Caliphs (632–661)

Leadership of the community then passed to a succession of caliphs (successors). In Sunni tradition, the first four — Abu Bakr, Umar, Uthman, and Ali — are honored as the Rightly-Guided (Rashidun) Caliphs, who led until 661 CE.345 Under them Islam expanded rapidly beyond Arabia. (See The Rightly-Guided Caliphs.)

Expansion and the great caliphates

After the Rashidun came two long-lived dynasties that carried Islam across continents: the Umayyad caliphate (661–750 CE), centered in Damascus, and the Abbasid caliphate (750–1258 CE), centered in Baghdad. Within roughly a century of the Prophet's death, Muslim rule stretched from Spain and North Africa across the Middle East to Persia and Central Asia.345

A golden age of learning

The Abbasid era in particular is remembered as a golden age: in centers such as Baghdad's House of Wisdom, scholars advanced mathematics, astronomy, medicine, philosophy, and the arts, preserving and building on the learning of earlier civilizations.345

Islam today

Across the centuries since, Islam spread through trade, scholarship, and travel far beyond its early heartlands — into Africa, South and Southeast Asia, and eventually every continent. Today it is the world's second-largest religion, with roughly 1.9 billion adherents.624

In short

From a single voice in 7th-century Mecca, Islam grew within decades into a world civilization under the Rashidun and the Umayyad and Abbasid caliphates, and across fourteen centuries into a global faith followed by nearly a quarter of humanity. The chapters that follow look more closely at the life of the Prophet ﷺ and at the Rightly-Guided Caliphs.