Oghulchak Arslan Khan (9th century) was the last Karakhanid ruler to follow the native Turkic religion of Tengrism.
He was a lesser Bughra Khan during his elder brother Bazir Arslan's rule in the west.
Growing Muslim presence led to the secret conversion of his nephew, Satuq Bughra Khan.
[2] The khagan, after seeing Satuq starting to build the temple, stopped him, believing that he had not converted.
Afterwards, Satuq obtained a fatwa which permitted him in effect to kill his uncle, after which he conquered Kashgar.