The capture of Tahert or the Siege of Tahert occurred on August 26, 909 AD, at the city of Tahert (present-day Tagdemt), when the Fatimid army led by Ghazwiyya ibn Yusuf besieged and toppled the city, leading to the end of the Rustamid state, the surviving population migrated to Ouargla, from where they later moved to the Mzab region in the 11th century.