الحاكم بأمر الله
The earliest recorded attempt to build a dam near Aswan was in the 11th century, when the Arab polymath and engineer Ibn al-Haytham (known as "Alhazen" in the West) was summoned to Egypt by the Fatimid Caliph, Al-Hakim bi-Amr Allah, to regulate the flooding of the Nile, a task requiring an early attempt at an Aswan Dam. His field work convinced him of the impracticality of this scheme.