The war in San Fierro began when the Da Nang Boys attempted to move into the city, trying to force the local Blood Feather Triad group out of the Chinatown district. The Mountain Cloud Boys, led by Wu Zi Mu, begins to extract revenge by employing Carl Johnson to hinder their operations in the city. This first includes picking up a package from Easter Bay Airport whilst avoiding a Da Nang Boys ambush. Carl then acts as a decoy, driving south into Whetstone, to allow Red Gecko Tong leader Ran Fa Li to escape Wu Zi Mu's apartment, as the Da Nang Boys had planned to murder Ran Fa Li when he left the apartment.
Wu Zi Mu then has Carl go on the offensive, first having him sneak onto a Da Nang Boys freighter docked in the Easter Bay and plant a bug on the freighter. Wu Zi Mu, after learning of their illegal traffic ring, sends Carl to deal with the Da Nang Boys leader The Snakehead. Carl and Little Lion attack the freighter in a helicopter but are shot down, with Carl again sneaking aboard, freeing the prisoners and killing The Snakehead. This is unlikely to have ended the conflict between the two gangs, however, events between the two gangs are not continued in the GTA San Andreas storyline.