According to Jet, the Rough Rhinos attacked the village where he use to live and killed his parents. This caused Jet's lifelong hatred of the Fire Nation. During this time there was Hundred-Year War where Fire Nation attempted its shot at global imperialism.
When Aang and his friends were sleeping, the Rough Rhinos surrounded them and attempted to capture them. However, they all managed to hop on Appa's back and escape the Rough Rhinos.
Later on, while Aang was placed on trial for what Avatar Kyoshi, one of his past lives did to their "great" leader Chin the Conqueror, the Rough Rhinos arrived to destroy the village, for the glory of Fire Lord Ozai. Despite this, all five of them were quickly defeated by Aang, Sokka, and Katara.
Some time after this, the Rough Rhinos encountered Zuko and Iroh, while they were fugitives of the Fire Nation. They planned to capture the two, so they could bring them to claim the bounty, but Zuko and Iroh managed to fend them off, and escape.
After the Hundred-Year War ended, the Rough Rhinos no longer serve Fire Nation, and work as freelance mercenaries. Mongke managed to recruit three new members named Utor, Seijir and Junho. They were seen working the personal security detail of the owners of the Earthen Fire Refinery named Lao Beifong and Loban. Old bad fates die hard: here Rough Rhinos would once again encounter Team Aang and renew their old hostilties, clashing with them - once again with Team Aang emerging as the victor.
Animation and Comics
- Colonel Mongke (Founder and Leader)
- Vachir - a former and disgraced member of Yuyan Archers.
Additional Members in Comics
- Utor - a former Fire Nation soldier who had a decent life under Fire Nation military. He holds grudge against Team Aang for terminating that fine life.