[4] The Yan River's source is Zhou Mountain (Chinese: 周山), in the town of Tianciwan [zh] Jingbian County, Yulin.

[5] The Yan River continues its flow south to Baota District,[6] the urban center of Yan'an.

During the Warring States period, the river was known as the Qushui (Chinese: 区水; pinyin: Qūshuǐ).

[4] Later, during the Western Han, the river was called the Weishui (Chinese: 洧水; pinyin: Wěishuǐ).

[4] Afterwards, in the Northern and Southern dynasties, and during the Western Wei, the river was known as the Qingshui (Chinese: 清水; pinyin: Qīngshuǐ).