Ecoregions of the world, spanning all land area (terrestrial) of the planet, were first defined and mapped in 2001 and subsequently revised in 2017. Later, freshwater ecoregions and marine ecoregions of the world were identified. Within India, there are 46 terrestrial ecoregions, 14 freshwater ecoregions, and 6 marine ecoregions. Terrestrial ecoregions The terrestrial ecoregions of the world include 45 ecoregions that fall entirely or partly within the boundaries of India. These ecoregions fall within two biogeographic realms: Indomalayan and Palearctic. They also fall under ten biomes: Deserts and Xeric Shrublands, Flooded Grasslands and Savannas, Mangroves, Montane Grasslands and Shrublands, Temperate Broadleaf and Mixed Forests, Temperate Conifer Forests, Tropical and Subtropical Coniferous Forests, Tropical and Subtropical Dry Broadleaf Forests, Tropical and Subtropical Grasslands, Savannas and Shrublands, and Tropical and Subtropical Moist Broadleaf Forests. The ecoregion Rock and Ice is not included under any specific biome or biogeographic realm. Freshwater ecoregions Freshwater ecoregions of the world have been defined as "a large area encompassing one or more freshwater systems with a distinct assemblage of natural freshwater communities and species. The freshwater species, dynamics, and environmental conditions within a given ecoregion are more similar to each other than to those of surrounding ecoregions, and together form a conservation unit." The following 14 freshwater ecoregions occur within India. Upper Indus Indus Himalayan Foothills Lower and Middle Indus Ganges Himalayan Foothills Middle Brahmaputra Chin Hills–Arakan Coast Ganges Delta and Plain Narmada–Tapti Northern Deccan Plateau Southern Deccan Plateau Southeastern Ghats Western Ghats Andaman Islands Nicobar Islands Marine ecoregions Marine ecoregions of the world have been described across the worlds oceans and seas. India's seas are in the Western Indo-Pacific marine realm. This includes the following four provinces and six marine ecoregions. West and South Indian Shelf province Western India South India and Sri Lanka Central Indian Ocean Islands province Maldives Bay of Bengal province Eastern India Northern Bay of Bengal Andaman province Andaman and Nicobar Islands Global 200 ecoregions in India The following are the ecoregions in India that are included in the Global 200 ecoregions: Terrestrial Chota Nagpur dry deciduous forests (India) Eastern Deccan Plateau moist forests (old name) or East Deccan moist deciduous forests (current name) (India) Eastern Himalayan alpine meadows (Bhutan, China, India, Myanmar, Nepal) Eastern Himalayan broadleaf forests (Bhutan, China, India, Myanmar, Nepal) Himalayan subtropical pine forests (Bhutan, India, Nepal, Pakistan) Naga-Manipuri-Chin hills moist forests (India) Northeast India-Myanmar pine forests (India, Myanmar)