Islam, 610 to 2020
From 610, the first revelation in Muslim tradition, to 2.0 billion Muslims in 2020: the expansion to 751, Sunni and Shia, and Pew’s growth data for 2010–2020.
By Muslim tradition Muhammad received his first revelation in 610, as Britannica reports it, and led his followers from Mecca to Medina, the Hijra, in 622. In 2020 there were 2.02 billion Muslims, 25.6% of the world, according to the Pew Research Center; their number rose by 347 million in the decade, more than any other group’s, as the overview shows.
The first expansion
Muhammad died in June 632. In the century after, armies under the caliphs took Egypt, entering Alexandria in 642, landed in Iberia in May 711 and reached Sind in 712. The Abbasids overthrew the Umayyad caliphate in 750, and an Arab army met a Tang Chinese army at Talas, in Central Asia, in 751 (Exhibit 16). The map shows rule, not belief: the sources cited do not date when the populations of these regions became majority Muslim.
16. Within 130 years of the Hijra, Muslim armies had reached Iberia, Sind and Central Asia
Source. “Muhammad” (summary); “Muhammad”; “Battle of Karbala”; “Amr ibn al-As”; “Tariq ibn Ziyad”; History 315 learner’s guide lesson 9; “The Battle of Talas”
Full sizeMethod. Points mark the city named in the cited source; arrows show the order of the dated events, not routes or the spread of conversion, which the sources do not date.
Sunni and Shia
Muhammad’s grandson Husayn was killed at the Battle of Karbala on October 10, 680, in Britannica’s dating. Pew’s most recent global estimate, from 2009, put Shia Muslims at 10–13% of all Muslims and Sunni Muslims at 87–90%; most Shia, between 68% and 80%, lived in Iran, Pakistan, India and Iraq, and Iran alone had 66 million to 70 million (Pew, 2009, Exhibit 17).
17. Shia Muslims were 10–13% of the world’s Muslims in Pew’s 2009 estimate, 154 million to 200 million people
Source. Pew Research Center, Mapping the Global Muslim Population, 2009.
Full sizeMethod. Pew gives ranges because most of its Shia figures rest on expert and ethnographic estimates rather than censuses; it has not published a newer global split.
Where Muslims live
Most Muslims do not live in the Middle East. Pew’s 2020 figures put 1.19 billion in the Asia-Pacific region and 414 million in the Middle East and North Africa. Indonesia, Pakistan, India and Bangladesh each had more than 150 million (Exhibit 18); India’s 213 million made up about 15% of its population. Muslims were a majority in 53 places (Exhibit 19).
18. Indonesia had the most Muslims in 2020, 239 million; Pakistan, India and Bangladesh followed
Source. Pew Research Center, Religious Composition by Country, 2010–2020, rounded counts.
Full sizeSource. Pew Research Center, Religious Composition by Country, 2010–2020, percentages. Country shapes: Natural Earth.
Full sizeMethod. Outlined places have no estimate.
Why the number grows
The fastest regional growth from 2010 to 2020 was in sub-Saharan Africa among large populations, 33.8%, and in North America from a small base, 52.3% (Exhibit 20). Pew attributes Muslim growth to age and fertility rather than conversion: about one in 100 adults raised Muslim has left Islam and a similar number has joined, in its surveys of 117 places. Muslims were the youngest of the seven groups Pew counts in 2020, with a median age of 24.1, and were younger than the population as a whole in each region Pew reports (Exhibit 21).
20. The Muslim population of sub-Saharan Africa rose by 34% between 2010 and 2020, to 369 million
Source. Pew Research Center, Religious Composition by Country, 2010–2020, rounded counts.
Full sizeMethod. North America’s rise is the largest in percentage terms from the smallest base.
21. Muslims were younger than the population as a whole in every region Pew reports; worldwide their median age was 24.1 years against 30.6 for all people
Source. Pew Research Center, 2025 report, p. 29.
Full sizeMethod. Median ages as published.
Limitations (4)
- Method. The arrival in Sind is dated 712 from the National Institute of Open Schooling (India); no Britannica page dating it was found.
- Coverage. No global count of Sunni and Shia Muslims newer than Pew’s 2009 estimate was found; it gives no separate figures for Ibadi Muslims or for Sufi orders.
- Coverage. The expansion map (Exhibit 16) shows dated conquests only; the timing of conversion in each region is not charted.
- Method. Pew’s Sunni and Shia figures are ranges built largely from expert estimates; no margin of error can be computed.
Sources (5)
- Encyclopaedia Britannica: “Muhammad” (summary); “Muhammad”; “Battle of Karbala”; “Amr ibn al-As”; “Tariq ibn Ziyad”; “Abbasid caliphate”
- King’s College London: “The Battle of Talas”
- National Institute of Open Schooling (India): History 315 learner’s guide lesson 9
- Natural Earth: Admin 0 country boundaries, 1:110m and 1:50m (via world-atlas 2.0.2)
- Pew Research Center: “How the Global Religious Landscape Changed From 2010 to 2020,” June 9, 2025; “How the Global Religious Landscape Changed From 2010 to 2020,” full report (PDF), 2025; Religious Composition by Country, 2010–2020, dataset and country table, 2025 (updated Feb. 12, 2026); “Mapping the Global Muslim Population,” Oct. 7, 2009
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