A maakond (county) is the biggest administrative subdivision. The county government (Maavalitsus) of each county is led by a county governor (Maavanem), who represents the national government at the regional level. Governors are appointed by the Government of Estonia for a term of five years. Several changes were made to the borders of counties after Estonia became independent, most notably the formation of Valga County (from parts of Võru, Tartu and Viljandi counties) and Petseri County (area acquired from Russia with the 1920 Tartu Peace Treaty).