Treaty ports were specific coastal cities in China and other countries that were opened to foreign trade and residence following various treaties, particularly after the Opium Wars. These ports allowed foreign powers to establish a presence and conduct commerce, often under favorable conditions that limited local authority. The establishment of treaty ports marked a significant shift in international relations during the 19th century. They facilitated the exchange of goods and ideas but also led to tensions and conflicts, as local populations often resisted foreign influence and control over their territories.