A young Temugin's mother re-married a man named Zhang who said he will help him on his journey to find the Makluan Rings. His mother eventually died after (it's not said specifically how she died, though strongly hinted that Zhang killed her), and to Temugin's rage, Zhang kept the ring for himself. He then used it to take the title of the Mandarin and formed his own criminal organization, the Tong. Some time ago, He and Howard Stark talked a while back about information on the Makluan Rings and his name was mentioned in Howard's diary.
When Zhang attempted to destroy Stark Tower, the plot is stopped by Iron Man. Zhang presumed that Stane had unleashed this hero to prevent him from taking the Makluan ring, which he presumably did not know its significance. Gene tried to convince Zhang not to be so judgemental. However, Zhang refused to tolerate such insolence in front of his men and warned Gene to be careful not to question him again, otherwise he will join Gene's Mom. Gene said that if he was smart, he'd start listening to him as he is a Khan. Zhang replied that he wears the Makluan ring and that Gene will never know what true power is because he is a child and a fool.
Gene eventually succeeded in taking back the ring and he imprisoned Zhang, posing as him in front of his men thanks to the Mandarin armor. As the new Mandarin, Gene successfully took another ring from Obadiah Stane. Gene tells Zhang that he should have listened to him when he had the chance.
Zhang's further appearances are when Gene Khan asks for his advice or answers to his questions like when he needed to know if Count Nefaria has seen his without the Mandarin armor in Pepper, Interrupted. Usually it ends with Zhang mocking him and his unworthiness of the Makluan Rings.
The Tong have been having doubts about their master's identity since their peace negotiation with the Maggia. They eventually found Zhang and released him from his imprisonment in the season finale, Tales of Suspense so he can overthrow Gene and claim all of the Makluan rings. He then orchestrates Tony and Pepper's capture and learns that the fifth ring is in Peru. Zhang ends up retreating when the Test of Sacrifice begins with the awakening of Fin Fang Foom. Afterwards, he is interrogated by Rhodes as War Machine.
Zhang's fate is unknown since he doesn't reappear in the series (except in a dream caused by the Grim Reaper).