Abu Zayd Ahmed ibn Sahl Balkhi (Persian: ??? ??? ???? ?? ??? ?????) was a Persian Muslim polymath: a geographer, mathematician, physician, psychologist and scientist.
Born in 850 CE in Shamistiyan, in the province of Balkh, Khorasan (in modern-day Afghanistan), he was a disciple of al-Kindi.
He was also the founder the "Balkhi school" of terrestrial mapping in Baghdad.