The Royal Burmese Army was a major Southeast Asian armed force between the 11th and 13th centuries and between 16th and 19th centuries. It was the premier military force in the 16th century when the Toungoo Dynasty built the largest empire in the history of Southeast Asia. The centuries-long warfare between Burma and Siam (1547–1855) shaped not only the history of both countries but also that of mainland Southeast Asia. In the 18th and early 19th centuries, highly militaristic Konbaung kings had built the largest empire in mainland Southeast Asia until they encountered the British in present-day northeast India. Prior to the three Anglo-Burmese wars (1824–1885), previous existential threats to the country had come from China in the form of Mongol invasions (1277–1301) and Manchu invasions (1765–1769).