东胡 / Donghu
东胡 / Donghu enters the wiki through 《资治通鉴·秦纪》114-3｜荆轲刺秦为何久久不行动？在等谁？ as the northern frontier opponent defeated by 秦开 in the episode’s background note on 秦武阳. The source says Qin Kai had once been a hostage among northern Hu peoples, then returned to 燕国 and forced Donghu back more than a thousand li.
For this ingest, Donghu matters mainly as part of Qin Wuyang’s inherited reputation. The page does not yet synthesize Donghu history beyond the source’s frontier-memory function.