The Suey Sing massacre was a gangland slaying that occurred in Chinatown, San Francisco in 1878 amid the "Tong Wars".
In the weeks following the 1878 Chinatown bombing, the Hop Wei Tong and the Long Zii Tong engaged in all-out war; Long Zii was assassinated - purportedly by Hop Wei - while a street fight between the two gangs left 11 dead. Over the next few months, a series of murders by an unidentified "Swordsman" (including Lance McCormick and Victor Timmons, the Teddy Boys, and other white San Franciscans) added to the San Franciscan public's fears of a violent "Yellow Peril" sweeping the city. Businessmen Lao Ting and Wang Chao brokered an agreement between the Hop Wei and Long Zii: there would be a duel between the two gangs' champions deciding whether Hop Wei would retain its monopoly on opium trafficking or if Long Zii would be given its own territory for the trade. The ensuing duel saw Long Zii's Li Yong defeat Hop Wei's Ah Sahm, leading to a period of peace during which time Ah Sahm - expelled from the Hop Wei - became a "coolie" laborer, while Long Zii grew its power through the drug trade.
Complicating this fragile balance of power was the Suey Sing Tong boss Lao Tze's decision to covertly deal opium on Long Zii turf. When Gao Chenghe was kidnapped by the Long Zii while dealing drugs, he revealed the Suey Sing's operations, resulting in Long Zii leader Mai Ling deciding to send Li Yong and Fung Hai Tong leader Zing Yuen to meet with Lao Tze and warn him against continuing his trade. Li Yong was content with Lao Tze heeding his warning, but Zing Yuen picked a fight by stabbing Lao Tze in the throat before the rest of his gang turned on the unsuspecting Suey Sing henchmen and massacred them within a few minutes. The massacre led to Li Yong angrily confronting Zing about what had happened, but Zing revealed that Mai Ling had sent him with Li Yong with the purpose of wiping out the Suey Sing.