《周书·列传·卷三十三》
当时与束魏争强斗胜，战争不停，蠕蠕族乘虚而入，屡次成为边防的忧患。
时与东魏争衡，戎马不息，蠕蠕乘虚，屡为边患。
At that time, the Eastern Wei and the Western Wei was competing for the strongest, and the war did not stop. The Rouran took advantage of the situation and repeatedly became a threat to the border defense.