Beyond the northern plains, the climate becomes more temperate, nurturing the fertile land which gave the old kingdom of the north the name of Lanna , "the land of a million rice fields". Until the beginning of the last century, Lanna was a largely independent region, with its own styles of art and architecture. Its capital, the cool, pleasant city of Chiang Mai , is now a major travellers' centre and the most popular base from which to organize treks to nearby hilltribe villages. Another great way of exploring the scenic countryside up here is to rent a motorbike and make the six hundred-kilometre loop over the forested western mountains into Mae Hong Son and back. Heading north from Chiang Mai brings you to the increasingly upmarket town of Chiang Rai , and then on to the Burmese border settlements of Mae Sai and Sop Ruak - better known as the apex of the "Golden Triangle" . You can't enter Burma here for longer than a day-trip, but Chiang Khong , on the Mekong River, is an important crossing point to Laos, with same-day but expensive visas available.