Yan, a vassal state of Zhou in modern Hebei and Liaoning
north Hebei
the four Yan kingdoms of the Sixteen Kingdoms, namely: Former Yan 前燕[Qian2 Yan1] (337-370), Later Yan 後燕|后燕[Hou4 Yan1] (384-409), Southern Yan 南燕[Nan2 Yan1] (398-410), Northern Yan 北燕[Bei3 Yan1] (409-436)
Definitions (Wiktionary)
name
Yan, an ancient march, duchy, and kingdom of northeastern China during the Zhou dynasty (syn.) 燕