Definitions
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 (337-370), Later Yan 後燕|后燕 (384-409), Southern Yan 南燕 (398-410), Northern Yan 北燕 (409-436)
surname Yan
swallow (family Hirundinidae)