Northern Thailand

Historically, northern Thailand has been linked to the Hariphunchai Kingdom, which emerged as a powerful state in the region in the 7th century. This kingdom was related to the Dvaravati that existed from the 6th to 11th centuries. The Hariphunchai culture later influenced the development of the Lanna Kingdom, which emerged in the 13th century and lasted until the 18th century.

Geography

North Thailand is bound by the Salween River in the west and the Mekong in the east. The basins of rivers Ping, Wang, Yom, and Nan, all tributaries of the Chao Phraya River, in the central part run from north to south and are mostly very wide. The basins cut across the mountains of two great ranges, the Thanon Range in the western part and the Phi Pan Nam in the eastern. Their elevations are generally moderate, a little above 2,000 metres (6,562 ft) for the highest summits. Although formerly forested, many of these mountains are now denuded.

Parallel mountain ranges extend from the Daen Lao Range, in the southern region of the Shan Hills, in a north–south direction, the Dawna Range forming the western border of Thailand between Mae Hong Son and the Salween River. To the east the Thanon Thong Chai Range, the Khun Tan Range, the Phi Pan Nam Range, as well as the western part of the Luang Prabang Range, form the natural region of the Thai highlands together with the former.

The high mountains are incised by steep river valleys and upland areas that border the central plain. A series of rivers, including the Nan, Ping, Wang, Yom, and Nan, flow southwards through mountain valleys and join to form the Chao Phraya in Nakhon Sawan Province in the central region. Sirikit Dam is on the Nan River in Uttaradit Province. The northeastern part is drained by rivers flowing into the Mekong basin, like the Kok and Ing.

The four-region system includes the northern parts of the central plain as well as some mountainous areas bordering the western and the northeastern limits. The total forest area is 90,228 km² (34,837 sq mi) or 52.5 percent of this four-region area.

National parks

Within the northern region there are some sixty national parks. Chiang Mai Province has nine national parks of which Doi Inthanon National Park with the country's highest mountain and Op Luang National Park have a scenic river canyon, waterfalls, and caves. Doi Khun Tan National Park, which is located midway between the two provincial capitals of province Lampang and Lamphun, is best known for Thailand's longest railroad tunnel, which is 1,352 metres (4,436 ft) long. Doi Phu Kha National Park in province Nan is northern Thailand's largest national park.