Tanah Datar Regency is a landlocked regency (kabupaten) in West Sumatra province, Indonesia. The regency has an area of 1,336 km2 and had a population of 338,484 at the 2010 Census, which rose to 371,704 at the 2020 Census. The official estimate as of mid-2022 was 376,276 - comprising 188,551 males and 187,725 females. The regency seat is the town of Batusangkar. The city of Padang Panjang is also geographically located within the regency but constitutes a municipality of its own.

West Sumatra is a province of Indonesia. It is on the west coast of the island of Sumatra and includes the Mentawai Islands off that coast. West Sumatra borders the Indian Ocean to the west, as well as the provinces of North Sumatra to the north, Riau to the northeast, Jambi to the southeast, and Bengkulu to the south. The province has an area of 42,119.54 km2 (16,262.45 sq mi),or about the same size as Switzerland,with a population of 5,534,472 at the 2020 census. The official estimate at mid 2022 was 5,640,629. The province is subdivided into twelve regencies and seven cities. It has relatively more cities than other provinces outside Java, although several of them are relatively low in population compared with cities elsewhere in Indonesia. Padang is the province's capital and largest city.