Tongyu (Chinese: 通榆; pinyin: Tōngyú) is a county of northwestern Jilin province, China, bordering Inner Mongolia to the south and west. It is under the administration of Baicheng City, 92 kilometres (57 mi) to the north-northwest, with a population of 350,000 residing in an area of 8,476 km2 (3,273 sq mi).The town of Tongyu can be considered to include the areas of Kaitong and Yangjing described below.