The Indomalayan Biogeographic Region consists of South Asia, Southeast Asia, Taiwan and southern China. The Hindu Kush, the Himalayas, and the Patkai range form the border to the Palearctic region. In Indonesia, it borders the Australasian region. The Indomalayan region is tropical, with exception of highlands, where climate is colder.

Indomalayan realm
The Indomalayan realm is one of the eight biogeographic realms. It extends across most of South and Southeast Asia and into the southern parts of East Asia.

Also called the Oriental realm by biogeographers, Indomalaya extends from Afghanistan through the Indian subcontinent and Southeast Asia to lowland southern China, and through Indonesia as far as Java, Bali, and Borneo, east of which lies the Wallace line, the realm boundary named after Alfred Russel Wallace which separates Indomalayan from Australasia. Indomalaya also includes the Philippines, lowland Taiwan, and Japan’s Ryukyu Islands.

Most of Indomalaya was originally covered by forest, mostly tropical and subtropical moist broadleaf forests, with tropical and subtropical dry broadleaf forests predominant in much of India and parts of Southeast Asia. The tropical moist forests of Indomalaya are mostly dominated by trees of the dipterocarp family (Dipterocarpaceae).

Major ecological regions
The World Wildlife Fund (WWF) divides Indomalayan realm into three bioregions, which it defines as “geographic clusters of ecoregions that may span several habitat types, but have strong biogeographic affinities, particularly at taxonomic levels higher than the species level (genus, family)”.

Indian Subcontinent
The Indian Subcontinent bioregion covers most of India, Pakistan, Bangladesh, Nepal, Bhutan, and Sri Lanka. The Hindu Kush, Karakoram, Himalaya, and Patkai ranges bound the bioregion on the northwest, north, and northeast; these ranges were formed by the collision of the northward-drifting Indian subcontinent with Asia beginning 45 million years ago. The Hindu Kush, Karakoram, and Himalaya are a major biogeographic boundary between the subtropical and tropical flora and fauna of the Indian subcontinent and the temperate-climate Palearctic realm.

Indochina
The Indochina bioregion includes most of mainland Southeast Asia, including Myanmar, Thailand, Laos, Vietnam, and Cambodia, as well as the subtropical forests of southern China.

Sunda shelf and the Philippines
Malesia is a botanical province which straddles the boundary between Indomalaya and Australasia. It includes the Malay Peninsula and the western Indonesian islands (known as Sundaland), the Philippines, the eastern Indonesian islands, and New Guinea. While the Malesia has much in common botanically, the portions east and west of the Wallace Line differ greatly in land animal species; Sundaland shares its fauna with mainland Asia, while terrestrial fauna on the islands east of the Wallace line are derived at least in part from species of Australian origin, such as marsupial mammals and ratite birds.

History
The flora of Indomalaya blends elements from the ancient supercontinents of Laurasia and Gondwana. Gondwanian elements were first introduced by India, which detached from Gondwana approximately 90 MYA, carrying its Gondwana-derived flora and fauna northward, which included cichlid fish and the flowering plant families Crypteroniaceae and possibly Dipterocarpaceae. India collided with Asia 30-45 MYA, and exchanged species. Later, as Australia-New Guinea drifted north, the collision of the Australian and Asian plates pushed up the islands of Wallacea, which were separated from one another by narrow straits, allowing a botanic exchange between Indomalaya and Australasia. Asian rainforest flora, including the dipterocarps, island-hopped across Wallacea to New Guinea, and several Gondwanian plant families, including podocarps and araucarias, moved westward from Australia-New Guinea into western Malesia and Southeast Asia.

Flora and fauna
Two orders of mammals, the colugos (Dermoptera) and treeshrews (Scandentia), are endemic to the realm, as are families Craseonycteridae (Kitti’s hog-nosed bat), Diatomyidae, Platacanthomyidae, Tarsiidae (tarsiers) and Hylobatidae (gibbons). Large mammals characteristic of Indomalaya include the leopard, tigers, water buffalos, Asian elephant, Indian rhinoceros, Javan rhinoceros, Malayan tapir, orangutans, and gibbons.

Indomalaya has three endemic bird families, the Irenidae (fairy bluebirds), Megalaimidae and Rhabdornithidae (Philippine creepers). Also characteristic are pheasants, pittas, Old World babblers, and flowerpeckers.

More information is available under Indomalayan realm fauna.

The Asian elephant (Elephas maximus) is the only elephant species which is regularly tamed.

The Asiatic lion (Panthera leo leo) is an endangered population of lion found mainly in the Gir Forest National Park in the western Indian state of Gujarat.

The Bengal tiger (Panthera tigris tigris) is the world’s most numerous tiger species, and the national animal of India and Bangladesh.

The leopard (Panthera pardus) was prevalent across the region, but is today endangered.

The orangutan (Pongo pygmaeus, Pongo abelii and Pongo tapanuliensis) is endemic to Indonesia.

The proboscis monkey (Nasalis larvatus) is a large monkey named for its exceptionally long nose. It lives only on the island of Borneo, and can be seen in all three countries (Malaysia, Indonesia, and Brunei) that divide the island. It generally lives in trees near water and is able to swim. They can be spotted easily from the rivers near Bandar Seri Begawan in Brunei and Bako National Park in Malaysia.

Macaques (Macaca) can be found in this region. They like to spend their time on the ground rather than in trees, though they may climb up a tree if you scare them. In areas with humans, you might see them trying to steal people’s food.

Birds
Pheasants (Phasianinae) are characteristic of south Asia.

The peafowl or peacock has two species in South Asia; the Indian Peafowl (Pavo cristatus) and the Green Peafowl (Pavo muticus).

Reptiles
Monitor lizards (Varanus) can be found in Indonesia and Malaysia. They are generally very big lizards, growing up to two meters or even more. Most live on land, but some can swim or climb trees. Though their size may be scary, they generally don’t attack humans unless threatened and will probably waddle away (at a surprising speed!) when they hear you coming. The largest that still exist are Komodo dragons, which can grow up to three meters and can be seen in Komodo National Park in Indonesia.

Destinations
Botanical tourism in Singapore
Indian National Parks and Wildlife Sanctuaries
Indian Zoos and Botanical Gardens