Known to the central Siamese as the Lao States at the turn of the 20th century, the northern region of what is now Thailand was an independent region known as the Lanna kingdom. The main city, Chiang Mai, was built in 1296 by King Mengrai. The city was abandoned in 1776??1 due to Burmese invasions, but became an acknowledged part of Siam around the same time. The north was linked to Bangkok only by river, a journey which could take some six months, until in 1922, a railway was completed which connected Bangkok and Chiang Mai.