Kūshyār ibn Labbān

In his book al‐Madkhal fī Ṣinā'at aṣkām al‐nujūm (Introduction to the Art of Astrology) the author calls himself Kūshyār ibn Labbān ibn Bāshahrī al‐Jīilī. This name indicates that Kūshyār was a son of Labbān who was a son of Bāshahrī and that he hailed from Jīlān, a region of modern Iran south of the Caspian Sea. The date of the book is some time around AD 992, the year for which positions of the fixed stars are given. In the same book he refers to his two earlier books on astronomical tables (zījes), al‐Zīj al‐jāmi' (Comprehensive) and al‐Zīj al‐bāligh (Far‐reaching). In some manuscripts "Abū al‐ṣasan" (the father of al‐ṣasan) is added at the top of his name. No further information is available about his family and life.

One of the most famous of his books is the Kitāb fī uṣūl Ṣisāb al‐hind (Book on the Principles of Hindu Reckoning) which is known as the oldest surviving Arabic book on arithmetic using Hindu numerals. The Arabic text is divided into two parts. In