The Treaty of Tientsin, signed in 1856, was an agreement between China and several Western powers, including Britain and France, that marked a significant point in the era of economic imperialism. This treaty opened additional ports to foreign trade, legalized the opium trade, and granted foreign powers extraterritorial rights in China. The Treaty of Tientsin exemplifies how Western nations exploited China's vulnerability, deepening their economic control and influencing Chinese sovereignty.