Pematangsiantar, and also known as the City of Pematangsiantar, is an independent city in North Sumatra Province of Indonesia, surrounded by, but not part of, the Simalungun Regency, making Pematangsiantar an enclave within Simalungun Regency. Pematangsiantar formerly had the status of a second-level district and was the administrative centre of the surrounding Regency, but in 1986 it was elevated to Kota and separated from the Regency.