now i got curious. this is from wookieepedia, so take it with a grain of salt.
andDurge was in exceptional physical shape already at an early age, and possessed a natural aggression uncharacteristic of the Gen'Dai species. After witnessing bounty hunters in action, Durge was filled with a lust for hunting. He eventually left his tribe and ventured out into the galaxy, where he trained under various crack bounty hunters. At one point, he met a Mandalorian training master known as Jaing, who taught Durge all he needed to know in the field of Mandalorian tactics and combat skill.
so essentially he was a mando and then snappedOver the centuries, Durge acquired a deep distaste for Mandalorians, and even killed their leader at one point. As a result of both personal tragedy and torture, he became increasingly mentally unstable.