《北齐书·列传·卷三十五》
西方的军队忽然来到，不久又退去，于是就跟随西师入鳃。
西师忽至，寻退，遂随西师入关。
The Western Army suddenly arrived but soon retreated, so he followed the Western Army into Qi.
<s>[INST] Explain the meaning of this Classical Chinese passage in English: 西师忽至，寻退，遂随西师入关。 [/INST] The Western Army suddenly arrived but soon retreated, so he followed the Western Army into Qi.</s>
Explain the meaning of this Classical Chinese passage in English: 西师忽至，寻退，遂随西师入关。
user
The Western Army suddenly arrived but soon retreated, so he followed the Western Army into Qi.
assistant