《汉书·志·地理志上》
洞束郡，盏固始置。
河东郡，秦置。
Dongdong County, established at the beginning of [the Han dynasty].
<s>[INST] Kindly elucidate the central themes in this passage in English: 河东郡，秦置。 [/INST] Dongdong County, established at the beginning of [the Han dynasty].</s>
Kindly elucidate the central themes in this passage in English: 河东郡，秦置。
user
Dongdong County, established at the beginning of [the Han dynasty].
assistant