The Montes Azules Integral Biosphere Reserve was decreed in 1978. It is located in the northeast of the state in the Lacandon Jungle. It covers in the municipalities of Maravilla Tenejapa, Ocosingo and Las Margaritas. It conserves highland perennial rainforest. The jungle is in the Usumacinta River basin east of the Chiapas Highlands. It is recognized by the United Nations Environment Programme for its global biological and cultural significance. In 1992, the Lacantun Reserve, which includes the Classic Maya archaeological sites of Yaxchilan and Bonampak, was added to the biosphere reserve.