Arakan is a coastal geographic region in Lower Burma. It comprises a long narrow strip of land along the eastern seaboard of the Bay of Bengal and stretches from the Naf River estuary on the border of the Chittagong Hills area (in Bangladesh) in the north to the Gwa River in the south. The Arakan region is about 400 miles (640 km) long from north to south and is about 90 miles (145 km) wide at its broadest. The Arakan Mountains (also called Arakan Yoma), a range that forms the eastern boundary of the region, isolates Arakan from the rest of Burma. The coast has several sizable offshore islands, including Cheduba and Ramree. The region's principal rivers are the Nāf estuary and the Mayu, Kaladan, and Lemro rivers. One-tenth of Arakan's generally hilly land is cultivated. Rice is the dominant crop in the delta areas, where most of the population is concentrated. Other crops include fruits, chilies, dha and tobacco.