In his Histoire des hommes instruits (Ta’rikh al-ḥukama), the historian al-Qifṭī (1172–1248) recounts how Indian numerals—and Indian methods of calculation—were introduced to the Arab world: "In the year one hundred and fifty-six [of the Hijra, that is, AD 773], a man from India appeared before the caliph al-Mansūr. He was highly proficient in the method of calculation known as sindhind [siddhanta in Sanskrit, the usual title of Indian astronomical treatises] […]. [All this was contained] in a work [...] bearing the name of one of the Indian kings called Figar, and whose calculations were accurate to one minute. Al-Mansūr ordered the work to be translated into Arabic and a new work to be composed from [this translation], which the Arabs could use as a basis for calculating the movements of the planets. This task was entrusted to Muḥammad ben Ibrahim al-Fazari […]. For [the later caliph al-Ma’mūn], Muḥammad ibn Musa al-Khwārizmī produced an abridged version of it."
Thus, perhaps around 825, al-Khwārizmī wrote one of the earliest Arabic books to include Indian numerals: the Livre de l’addition et de la soustraction d’après le calcul indien.
A Latin bestseller ------------------------
Although the original Arabic version of this book is now lost, many Latin translations and adaptations have fortunately survived.
Adelard of Bath (see the article) is sometimes credited with the first—or at least the earliest known—partial Latin translation of the Arabic text: the Liber Ysagogarum Alchorismi, or "al-Khwārizmī's Book of Introductions," which dates from around 1143.