Indomalaya is one of the world’s eight major biogeographical realms and has 3 subrealms -- the Indian Subcontinent, Southeast Asian Forests, and Malaysia & Western Indonesia -- with 18 bioregions in total based on the Bioregions 2020 framework. With its dense rainforests, this is one of the most important areas for biodiversity in the world, sheltering one-fifth of the Earth’s plant, animal and marine species. The region contains three mega-diverse countries — Indonesia, Malaysia and the Philippines — where four of the world's 25 biodiversity hotspots are located. The Indian Subcontinent in the west is capped by the long, curving mountain range of the Himalayas and includes dry forests, scrublands, and deserts up to the Arakan mountain range. The Southeast Asia subrealm, dominated by subtropical evergreen forests, encompasses the entire Indochinese Peninsula extending northward to the edge of the Yunnan-Guizhou plateau in China. This subrealm also includes the South China Sea and the Philippines. Farther south, the Malaysia & West Indonesia subrealm is dominated by moist broadleaf forests and coastal mangroves, containing hundreds of islands.