The Terai-Duar savanna and grasslands is a narrow lowland ecoregion at the base of the Himalayas, about wide, and a continuation of the Indo-Gangetic Plain in India, Nepal and Bhutan. It is colloquially called Terai in the Ganges Basin east to Nepal, then Dooars in West Bengal, Bhutan and Assam east to the Brahmaputra River. It harbours the world's tallest grasslands, which are the most threatened and rare worldwide.