Tipperary is the sixth-largest of the 32 counties by area and the 12th largest by population. It is the third-largest of Munster's 6 counties by both size and population. It is also the largest landlocked county in Ireland. The region is part of the central plain of Ireland, but the diverse terrain contains several mountain ranges: the Knockmealdown, the Galtee, the Arra Hills and the Silvermine Mountains. Most of the county is drained by the River Suir; the north-western part by tributaries of the River Shannon; the eastern part by the River Nore; the south-western corner by the Munster Blackwater. No part of the county touches the coast. The centre is known as 'the Golden Vale', a rich pastoral stretch of land in the Suir basin which extends into counties Limerick and Cork.