Langfang is a prefecture-level city of Hebei Province, and was known as Tianjin Prefecture until 1973. It was renamed Langfang Prefecture after Tianjin became a municipality and finally upgraded into a prefecture-level city in 1988. Langfang is located approximately midway between Beijing and Tianjin. At the 2020 census, the population of Langfang was 5,464,087, of whom 1,147,591 lived in the built-up area made of Guangyang and Anci districts; its total area is around 6,417.28 km2 (2,477.73 sq mi). Langfang borders Baoding to the southwest, Cangzhou to the south, Beijing to the north and Tianjin to the east. Sanhe City and Dachang Hui County are now conurbated with Beijing, so that they form part of the same built-up area. Langfang is the smallest prefecture-level city of Hebei Province by land area.

Tianjin is a municipality and metropolis in Northern China on the shore of the Bohai Sea. As such, it is not part of a province of China. It is one of the nine national central cities in Mainland China, with a total population of 13,866,009 inhabitants at the time of the 2020 Chinese census. Its metropolitan area, which is made up of 12 central districts, was home to 11,165,706 inhabitants and is also the world's 29th-largest agglomeration and 11th-most populous city proper.