Sinak was a member of a tribe of primitive humans that live within the Canyon of the Cave Men in Lost Valley. He was impulsive and quick to anger. When Turok and Andar taught the tribe how to craft and use bows, Sinak struggled to make his bow faster than the others, ruining good wood in the process. When testing day came, Sinak, in an attempt to shoot arrows incredibly hard, pulled too hard on the bowstring, snapping the wood.