Its mountain ranges are part of the system of hills extending through Laos, Burma, and China and linking to the Himalayas, of which they may be considered foothills.

The highlands in the north of Thailand are characterized by a pattern of generally steep hill ranges, intermontane basins and alluvial gorges.

Towards the Lao border, the divide to the Mekong basin becomes higher with peaks occasionally rising above 1,500 metres (4,900 ft) and streams flowing in narrow steep valleys.

[7][8] For centuries the Thai highlands have been inhabited with hill tribes mostly from Chinese or Tibeto-Burman descent, such as the Akha, Yao, Lahu, Khmu, Hmong and Lisu.

[9] These human groups immigrated into this relatively empty region fleeing persecution or harsh central rule in their respective environments, as well as seeking new land for their shifting agricultural productions system.

[13] The smoke produced by these fires is the main cause of the intense seasonal air pollution in the Thai highlands, also known as the "northern haze".

[16] Presently large tracts of the mountains are covered with a mixed vegetation resulting from the capacity of the efficient shifting agricultural system being exceeded.