The Sundarbans is a natural region comprising southern Bangladesh and a part in the Indian state of West Bengal. It is the largest single block of tidal halophytic mangrove forest in the world. The Sundarbans covers approximately 10,000 square kilometres (3,900 sq mi) most of which is in Bangladesh with the remainder in India. Sundarbans South, East and West are three protected forests in Bangladesh. This region is densely covered by mangrove forests, and is the largest reserves for the Bengal tiger.