Coyn was the leader of the Bear Men. As a child, he and his best friend Shalin decided to build a stone temple.
As leader of the Bear Men, Coyn conquered a nearby tribe to use as forced labour. When a slave was killed by a falling stone, Coyn wanted to sacrifice their leader, Dorlan. Dorlan was rescued by Sam Jones while the Eighth Doctor met with Coyn and Shalin. Shalin wanted the Doctor to kill the insane Coyn, but Coyn killed Shalin instead.
The Doctor convinced Coyn to let Dorlan's people go. In spite of a rebellion by the slaves, Coyn took the Doctor's advice. (PROSE: The People's Temple)