代国 / Dai State
代国 / Dai State appears in 《资治通鉴·周纪》04｜豫让 为智瑶复仇 as the polity conquered by 赵无恤 / 赵襄子. The episode stresses the kinship betrayal: the Dai ruler is Zhao Wuxu’s brother-in-law, and Zhao uses a family banquet setting to kill him and absorb Dai.
The conquest is not presented as clean strategic expansion. Zhao Wuxu’s sister kills herself after the attack, so the source reads the episode as both a state-building move and a human tragedy inside the ruling family.