Yanjin County (simplified Chinese: 盐津县; traditional Chinese: 鹽津縣; pinyin: Yánjīn Xiàn) is located in the northeast of Yunnan Province, China, bordering Sichuan Province to the north and east.

Situated on the banks of the narrow Heng River[1][a] valley, a tributary of the Yangtze, the town of Yanjing, Yanjin's county seat, has been referred to as the "World's Narrowest City.

"[2][3] The buildings of the city are situated on tall pillars, which is a preemptive measure toward water-level rise during periods of heavy flooding.

[5] During a Duanwu Festival celebration in the late 1800s or early 1900s at Yanjin, a bridge that spanned the Heng River collapsed and four hundred people were drowned.

[4] In July 2006, a 5.1 magnitude earthquake left 22 dead, 106 injured and more than 6,000 homes demolished.