อุทยานแห่งชาติเขาใหญ่

Around 1922 some people from Ban Tha Dan and Ban Tha Chai villages in Nakhon Nayok Province built a settlement within the forest in the Sankamphaeng mountains. Up to 30 households cultivated the land. The area was formally recognized by the government and classified as Tambon Khao Yai within Pak Phli District.

Due to its remoteness from the authorities it became a refuge for criminals and fugitives. After an attempt to capture the suspects in the area, in 1932 the villagers were relocated into the plains some 30 km away and the tambon status was cancelled.

In 1959 the prime minister, Field Marshal Sarit Thanarat, instructed the Ministry of Agriculture and the Ministry of the Interior to create a process whereby national parks could be established.

Nong Pak Chee grassland

Khao Yai National Park was then established on 18 September 1962, declared by royal proclamation in the Government Gazette (Book 79, Section 89) as the first national park in Thailand. A major role in its establishment was played by Boonsong Lekakul, one of the 20th century's most famous Thai conservationists. It was named after the defunct tambon, Khao Yai.

In 1984 the park was made an ASEAN Heritage Park, and on 14 July 2005 the park, together with other parks in the same range and in the Dong Phaya Yen Mountains further north, was proclaimed a UNESCO World Heritage Site under the name "Dong Phaya Yen–Khao Yai Forest Complex". As the lands adjacent to the national park are becoming increasingly developed into luxury hotels and golf courses, acquiring land for future wildlife conservation efforts is becoming problematic. Homes and residential villas have been built illegally within the limits of the protected area of the forest.^[3] Illegal logging is also a problem in the area of the park.^[4]