The Bison Rustlers are poachers working under Earth Queen Hou-Ting that primarily hunt for sky bison, because they are endangered and thus are prized. The poached animals are then sold as exotic food in Ba Sing Se, which is popular among the richer citizens there, as well as the Earth Queen. They make an appearance in the episode "Original Airbenders". Their leader is Ganbat, who wears a sky bison pelt on his back.
With the arrival of the new airbenders, they had to operate in secret, and were eventually discovered by Jinora and Kai. They planned to sell them both to the Earth Queen for her airbending regiment along with the bison. Jinora sent a spirit to Bum-Ju to warn Bumi and the others that she was in danger. Kai breaks free from his own cage and attempts to stop Ganbat from escaping with Jinora and the bison. He was forced to surrender when he saw that Tenzin and other sky bison were after him, and he and his fellow poachers are then locked in their own cages.