东周国 / Eastern Zhou Polity
东周国 / Eastern Zhou polity appears in 《资治通鉴·周纪》16丨孙膑庞涓恩怨纠葛 桂陵之战 as the target of a 韩国 attack in 353 BCE. The episode distinguishes this small polity from the broader Eastern Zhou historical period by explaining that the weakened 周王室 realm had split into eastern and western Zhou governments.
The page is source-scoped. Its role is to keep the episode’s “韩攻东周” notice from being flattened into dynasty-period language. It belongs with 西周国 and 东周西周分裂 as evidence of the royal house’s territorial and political contraction.