Natchitoches is a city in and the parish seat of Natchitoches Parish, Louisiana, United States. Established in 1714 by Louis Juchereau de St. Denis as part of French Louisiana, the community was named after the Natchitoches Indian tribe. The City of Natchitoches was first incorporated on February 5, 1819. It is the oldest permanent settlement in the Louisiana Purchase. Natchitoches's sister city is Nacogdoches, Texas. The population was 17,865 at the 2000 census.