Chittagong /tʃɪtəɡɒŋ/ is the second-largest city and principal seaport of Bangladesh. It is located at the estuary of the Karnaphuli River in southeastern Bangladesh and faces the Bay of Bengal on its western coastline. The Chittagong Metropolitan Area has an estimated population of over 6.5 million people. It serves as the administrative capital of Chittagong Division.With an ancient natural harbour, Chittagong has served as a gateway of Bengal since antiquity. It was described by the Roman geographer Claudius Ptolemy as one of the great harbours of Asia. For centuries, it was an important port on historic Asian and Indian Ocean trade routes— attracting merchants and travelers from Arabia, Persia, China and Southeast Asia. The Sultanate of Bengal and the Kingdom of Arakan ruled the region during the Middle Ages. The Portuguese established merchant settlements in the port city during the 16th-century. Following Mughal conquest in 1666, the city was renamed by the Mughal emperor Aurangazeb as Islamabad. In the late-18th century, the British East India Company gained authority of the port after the fall of the last independent Nawab of Bengal.By the late 1800s, Chittagong was a major administrative and transportation centre in the Bengal Presidency in British India. It was a focal point of the anti-colonial movement and witnessed the Chittagong armoury raid in 1930. It was a key base for Allied Forces during the Burma Campaign in World War II. After the Partition of British India in 1947, Chittagong became part of East Pakistan. During the Bangladesh Liberation War in 1971, the declaration of Bangladesh’s independence was proclaimed from the Free Bengal Radio Station in the city. Chittagong is an important commercial and industrial centre, being home to many of Bangladesh's oldest and largest companies, as well as the country's most diversified industrial base. The Port of Chittagong handles 80% of Bangladesh's foreign trade. In recent years, the metropolitan region of Chittagong has emerged as one of the fastest-growing cities in the world. With the development of Chittagong Port and the opening of new trade routes, the city has ambitions of emerging as a leading regional and global economic hub. It is seen as crucial to the economic development of landlocked southern Asia, including North East India, Southwest China, Nepal, Bhutan and parts of Burma.