《宋史·本纪·卷十二》
到了西夏侵犯边疆，就把他们赶出国境；契丹背弃盟约，就增加岁币。
至于夏人犯边，御之出境；契丹渝盟，增以岁币。
When Western Xia invaded the border, he drove them out of the country; when Khitan broke the treaty, he increased the annual tribute.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 至于夏人犯边，御之出境；契丹渝盟，增以岁币。 [/INST] When Western Xia invaded the border, he drove them out of the country; when Khitan broke the treaty, he increased the annual tribute.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 至于夏人犯边，御之出境；契丹渝盟，增以岁币。
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When Western Xia invaded the border, he drove them out of the country; when Khitan broke the treaty, he increased the annual tribute.
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