Though all the countries in Southeast Asia are independent as of 2014, only Thailand retained its independence during the Colonial Era. However, Thailand, which was known as Siam at the time, was still heavily influenced by the imperialist powers that colonized the rest of Southeast Asia.
Despite its nominal independence, Thailand signed a number of treaties with European powers and the United States. According to the Encyclopedia Britannica, the first of these was the Bowring Treaty. Signed in 1855, this treaty with the United Kingdom eliminated all trade restrictions, allowed separate law courts of British subjects and established a British consulate in Bangkok. Following this, Western advisers began flooding into the country to modernize it, and British and French forces began to slice away portions of Siam. However, because it acted as an effective buffer state between British Burma and French Indochina, the Thais preserved some ability to control their own affairs.