Most of Bangladesh is covered by the Bengal delta, the largest delta on Earth. The country has 700 rivers and 8,046 km (5,000 mi) of inland waterways. Highlands with evergreen forests are found in the northeastern and southeastern regions of the country. Bangladesh has many islands and a coral reef. The longest unbroken natural sea beach of the world, Cox's Bazar Beach, is located in the southeast. It is home to the Sundarbans, the largest mangrove forest in the world. The country's biodiversity includes a vast array of plant and wildlife, including endangered Bengal tigers, the national animal.
The etymology of Bangladesh (Country of Bengal) can be traced to the early 20th century, when Bengali patriotic songs, such as Namo Namo Namo Bangladesh Momo by Kazi Nazrul Islam and Aaji Bangladesher Hridoy by Rabindranath Tagore, used the term. The term Bangladesh was often written as two words, Bangla Desh, in the past. Starting in the 1950s, Bengali nationalists used the term in political rallies in East Pakistan. The term Bangla is a major name for both the Bengal region and the Bengali language. The earliest known usage of the term is the Nesari plate in 805 AD. The term Vangaladesa is found in 11th-century South Indian records.
The origins of the term Bangla are unclear, with theories pointing to a Bronze Ageproto-Dravidian tribe, the Austric word "Bonga" (Sun god), and the Iron Age Vanga Kingdom. The Indo-Aryan suffix Desh is derived from the Sanskrit word deśha, which means "land" or "country". Hence, the name Bangladesh means "Land of Bengal" or "Country of Bengal".