volcanic mountainous region in central Madagascar (Malagasy), covering an area of approximately 2,000 square miles (5,200 square km) and rising to 8,671 feet (2,643 m) in Mount Tsiafajavona, the nation's second highest peak. The main range runs south-southwest from the town of Antananarivo. Antsirabe (q.v.), situated on the slopes of Mount Tsiafajavona, is the principal town in the region.