Descended from a Turkish prince of Jurjan as-Suli is known as one of the greatest (shatranj) chess masters of the Arab world. For over 600 years his reputation remained unchallenged.
It was during the reign of al-Muktafi, (Caliph of Baghdad from 902 - 908 A.D.) that as-Suli came to prominence. A chess tournament was arranged between the court champion, al-Mawardi, and as-Suli. Though the Caliph clearly favored (and encouraged) al-Mawardi during the game as-Suli conclusively defeated him leaving no doubt as to who was the better player.
After winning the tournament the Caliph transferred his favor to as-Suli, dismissing al-Mawardi with the pun, "your rose-water [maward] has turned to urine!"
as-Suli remained popular at court for three reigns (al-Muktafi, al-Muqtadir and al-Radi). After al-Radi's death he fell from favor due to his sympathies for the 'Alids (Shi'ites). He was forced from Baghdad to Basra, where he eventually died in poverty in 946 A.D.
as-Suli was the first player to try to discover the science behind the game and his book Kitab Ash-Shatranj (Book of Chess) documents ten standard openings, common problems in middle play, and a collection of end plays with comments. A collection of manuscripts also survives in which games played by as-Suli are documented. It is the existance of these records that allow us to recognize as-Suli for the great chess master that he was.
as-Suli created a sharanj problem known as "as-Suli's Diamond" that went unsolved for over a thousand years. It was not until the mid-1980's when it was solved by Russian Grandmaster Yuri Averbakh.
Sources:
Robert Charles Bell (1980). Board and Table Games from Many Civilizations. ISBN 0-486-23855-5
Wikipedia - Abu-Bakr Muhammad ben Yahya as-Suli