Northern Thailand, or more specifically Lanna, is geographically characterised by several mountain ranges, which continue from the Shan Hills in bordering Myanmar to Laos, and the river valleys that cut through them.

Like most of Thailand, it has a tropical savanna climate, but its relatively high elevation and latitude contribute to more pronounced seasonal temperature variation, with cooler winters than the other regions.

[8] The high mountains are incised by steep river valleys and upland areas that border the central plain.

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.

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.

However, in the six-region classification system, it is the second largest native language in Northern Thailand, amounting to roughly two hundred thousand people, found in the lower part of Uttaradit Province.

Central Thai spoken in southern regions of Northern Thailand in the four-region classification system comprise a group of dialects classified as Ne.