Thungyai-Huai Kha Khaeng

The Thung Yai and Huai Kha Khaeng Wildlife Sanctuaries lie in the provinces of Uthai Thani, Tak and Kanchanaburi, in western Thailand, along the Myanmar border and some three hundred kilometres north-west of Bangkok. They were established as separate sanctuaries in 1972 and 1974 respectively, and UNESCO inscribed the pair on the World Heritage List in 1991.

At 622,200 hectares it is the largest conservation area in mainland South-East Asia and one of the least accessible and least altered forest zones in Thailand. It contains examples of almost every forest type in the region, and its flora and fauna combine associations found nowhere else, with species of Sino-Himalayan, Sundaic, Indo-Burmese and Indochinese affinity mixed within the same territory, many of them rare, threatened or endemic.

It holds 77% of the region's large mammals, including elephant and tiger, 50% of its large birds and 33% of its land vertebrates. It covers the headwaters of two important river systems, the upper Kwae Yai and the Huai Kha Khaeng, and the feature that gives Thung Yai its name — "great field" — is a central grassland plain of some 14,000 hectares. The pair is the core of the Western Forest Complex, made up of seventeen protected areas totalling 18,730 km², the largest in Thailand.