Thailand is the world's 49th-largest country, It is home to several distinct geographic regions, partly corresponding to the provincial groups. It is a country of southeast Asia on theGulf of Thailand(formerly the Gulf of Siam), an arm of the South China Sea. A Thai state was first established in the region in the mid-14th century but was often dominated by other powers during the succeeding centuries. It became a constitutional monarchy in 1932. Bangkok is the capital and the largest city. Population, 62,828, 706.