The Islamic religion took shape in Arabia nearly 1,400 years ago, and it was ﬁrst spread by Arab conquests. Its scriptures are in Arabic. Mecca, in Saudi Arabia, is its holiest shrine, to which vast numbers of Muslims make a pilgrimage (haj ). But only a ﬁfth of the world’s 1.3 billion Muslims are Arabs. There are more Muslims in India, Pakistan and Bangladesh than in the Arab countries. And not all Arabs are Muslim.