《史记·三十世家·赵世家》
二十一年，攻打中山国。
二十一年，攻中山。
In the 21st year, he attacked the Zhongshan state.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 二十一年，攻中山。 [/INST] In the 21st year, he attacked the Zhongshan state.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 二十一年，攻中山。
user
In the 21st year, he attacked the Zhongshan state.
assistant