Treaty of Nanking
Britain had acquired extraterritorial rights in China under the Treaty of Nanking in 1842. The United States obtained further extraterritorial rights under the Treaty of Wanghsia, which Britain was able to take advantage of under the Most Favoured Nation provision in a Supplemental Agreement to the Treaty of Nanking. Subsequently, under the Treaty of Tientsin, these rights were provided for directly in a Sino-British Treaty. In 1858, Britain obtained extraterritorial rights in Japan under the Anglo-Japanese Treaty of Amity and Commerce.