largest continuous tableland in Malaŵi. Its area of 9,000 square miles (23,310 square km) is bordered by the Chimaliro Hills and Viphya Mountains on the north, the Great Rift Valley on the east, the Dwangwa River on the west, and the Kirk and Dzalanyama ranges on the south. The highlands, rising out of the east-central area, have a gently undulating surface with heights varying from 2,500 feet (760 m) to 4,500 feet (1,400 m). The highlands' west-central area is dotted with hills of remarkably uniform elevations of 4,700 (1,430 m) to 5,000 feet (1,500 m). The broad valleys of the Lilongwe, Bua, and Dwangwa rivers traverse the region in an east-northeast direction. Their tributaries spread out in nadambo (bogs), offering little free-flowing water. The greater part of the Central Region Plateau has poor, sandy soils supporting grasslands and a sparse agricultural population. The fertile clays of the Lilongwe area, however, produce Malaŵi's major tobacco crop.