Seljuq power deteriorated with the Mongol invasions from the east. The Ilkhanate commanders in Anatolia then gained strength and authority and this encouraged the beys to declare sovereignty. With the fall of Seljuq centralized power in Konya, many beys joined forces with the atabegs (former Seljuq leaders) and other religious Muslim leaders and warriors from Persia and Turkistan which were fleeing the Mongols that were invading the Byzantine empire. To maintain control of their new territory, these reestablished beys employed Ghazi warriors from Persia and Turkestan, who also fled the Mongols. The ghazis fought under the inspiration of either a mullah or a general, trying to assert Islamic power, their assaults of the reestablished beys upon the Byzantine Empire reaching even further expanded the power sphere of the beyliks.