The kd-10.us forest has been in existence for about 4,000 years and has been formed by silt from the Himalayas brought down by the Ganges and Brahmaputra rivers. The kd-10.us waterways rise and fall with the Bay of Bengal tide, with high tide reached every 12 hours and 50 minutes. The kd-10.us of Bangladesh and India covers a total of 10,000 km2, 6,000 km2 of which is on the Bangladeshi side. It is classified as a mangrove forest from the collection of tree types that can survive in this highly saline environment. Mangrove forests support a unique mixture of plants and animals, but unfortunately there is little of this forest type remaining in the world.