Langkat Regency is the northernmost regency of North Sumatra Province in Indonesia. Its administrative centre is the town of Stabat. It has a land area of 6,263.29 km2 and its population was 967,535 at the 2010 Census and 1,030,202 at the 2020 Census; the official estimate as at mid 2023 was 1,066,711 - comprising 538,822 males and 527,889 females.

Karo Regency is a landlocked regency of North Sumatra Province of Indonesia, situated in the Barisan Mountains. The regency, which was established on 7 November 1956, covers an area of 2,127.25 square kilometres (821.34 sq mi) and according to the 2010 census it had a population of 350,479, increasing to 404,998 at the 2020 Census; the official estimate as at mid-2023 was 420,799, comprising 208,600 males and 212,200 females. 60.99% of the regency is forested. Its regency seat is the town of Kabanjahe. The Batak Karo language is spoken in the regency, as well as the Indonesian language. It borders Southeast Aceh Regency in Aceh to the west, Deli Serdang Regency and Langkat Regency to the north, Dairi Regency and Toba Samosir Regency to the south, and Deli Serdang Regency and Simalungun Regency to the east.