Dong Phaya Yen is a natural World Heritage site of international significance. It encompasses several national parks, including Khao Yai. Historically, it was known as Dong Phaya Fai (Jungle of the Fire Lord) due to its rugged terrain and deadly jungle fevers that terrified travelers. King Pinklao later changed the name to Dong Phaya Yen (Jungle of the Cold Lord) to symbolize auspiciousness and the newfound coolness as transportation began to penetrate the region. Today, this vast forest serves not only as a natural barrier between central Thailand and the Northeast but also as one of Southeast Asia's most vital biodiversity hotspots, consistently attracting visitors to experience its enduring richness and tranquility.