The country was officially named the Kingdom of Siam during the reign of King Mongkut, Rama IV, in the mid-nineteenth century.
Apparently, its origin is based in the Portuguese translation of the Chinese term used to refer to the Kingdom of Ayutthaya, which was something like ‘HSIEN‘.
Thus we can speak of the Kingdom of Siam from the mid-fourteenth century. The truth is that it sounds lovely and exotic.
Nevertheless, considering that it was the same people and that there was continuity between the kingdoms of Sukhothai and Ayutthaya, it’s usual to refer to the two cities as the capitals of the Kingdom of Siam. It is not accurate, but it is simpler.
Later, in 1949, after heated debates not yet closed, the name was changed to the Kingdom of Thailand, the land of free men.
We have a brief post about the history of Thailand, we offer 4 historical references to place the visits and excursions in Sukhothai and Ayutthaya.