Timurid Invasions
The Timurid Shah Rukh took advantage of the weakened state of the Kara Koyunlu to invade their land, crossing the Aras River and defeating the forces of Iskander and Ispend in a battle at Yahsi (28–29 July 1421). He briefly occupied Azerbaijan and Armenia but then withdrew once more to Khorasan. At this point, Ispend quickly re-occupied Tabriz. However Iskander followed him and fought with him, taking the city and establishing himself as ruler of the Kara Koyunlu. In 1429 Shah Rukh returned and occupied Tabriz, installing the Kara Koyunlu prince Abu Sa’id as his vassal. However, two years later Qara Iskander reoccupied Tabriz and had Abu Sa’id executed.
Read more about this topic: Qara Iskander