An inscription found in Oltu’s castle has been dated to the 7th century A.D.(see below), but the settlement is known to have been established much earlier. The city-fortress had once belonged to the Mamikonian "nakharars" and later passed into the hands of the Bagratunis. Administratively, it was found within the borders of the region of Vok'aghe in the province of Tayk. The first mention of Oltu as a fortified settlement is in the 9th century when the Georgian Bagratids occupied this region. After the death of the Iberian Kuropalates David in 1000, the troops of Emperor Basil II occupied the castles and towns in the region of Tao-Tayk‛, which included Oltu. In the following centuries, Oltu successively passed into the control of the Seljuk Turks, the Mongols and Turkmen tribes. The Ottomans conquered Olti from the Georgians in the sixteenth century.