Qara Iskander ibn Yusuf ruled the Kara Koyunlu or Black Sheep Turcoman tribe from 1420 to 1436. His struggles with the Timurid ruler Shah Rukh show that he was a brave leader, but he was not able to continue developing what he inherited from his father Qara Yusuf and his reign saw the decline and attenuation of the Kara Koyunlu.
Qara Yusuf’s death in 1420 left his sons Ispend bin Yusuf, Iskander, Jahan Shah and Abu Sa’id bin Yusuf fighting over the succession. The Sa’dlu tribe, one of the main sub-tribes of the Kara Koyunlu, declared Ispend as the new chief. Abu Sa’id had to flee and Jahan Shah went to Baghdad. Iskander and Ispend joined together to fight the Ak Koyunlu who were invading from the west, and defeated them.
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.
In 1436 Shah Rukh once more installed a Timurid governor in Tabriz, this time Qara Iskander’s brother Jahan Shah. Iskander marched on Tabriz but was defeated by Jahan Shah at Sufiyan to the north of the city, having been betrayed by some of his emirs. He then fled and took refuge in the castle of Alincak. Jahan Shah besieged the castle, and during the siege Iskander was murdered by his own son Shah Kubad.