What is "yanjiao"

Yanjiao is a town under the administration of Sanhe City in central Hebei province, bordering Tongzhou District, Beijing across the Chaobai River to the west, located east of Tiananmen Square and west of Sanhe. It has a population of 250,000, with long-term residents accounting for 147,000 and migrants taking the rest; 97.9% of the population is of Han ethnicity. , it has 55 villages under its administration.