In 1984, Tan was captured by the Soviets in Northern Kabul, Afghanistan. Venom Snake later rescued him due to his possessing abilities useful to Diamond Dogs. Although he was successfully rescued, he ended up getting captured on several more occasions, and again required saving.
Behind the scenes
Ziang Tan is a major character in the "Unlucky Dog" series of Side Ops in Metal Gear Solid V: The Phantom Pain. He's one of the few members of Diamond Dogs unable to be dismissed by the player. He also cannot be seen and interacted with while on Mother Base.
He first appeared in the E3 2014 demo of The Phantom Pain. He is based on the level designer of the same name. Tan being captured repeatedly is a running gag in the game.
Tan's character model during the "Unlucky Dog" missions were later reused for the "Bound Dragons" Event FOB, more specifically for the prisoner found in the first deck of the FOB platforms.