《明史·本纪·卷二》
庚寅日，扩廓帖木儿进攻兰州，指挥于光死难。
庚寅，扩廓帖木儿攻兰州，指挥于光死之。
On the day of gengyin, Kuoketuo Timur attacked Lanzhou, and the commander Yu Guang died in battle.
<s>[INST] Identify the key themes in this Classical Chinese text and explain them in English: 庚寅，扩廓帖木儿攻兰州，指挥于光死之。 [/INST] On the day of gengyin, Kuoketuo Timur attacked Lanzhou, and the commander Yu Guang died in battle.</s>
Identify the key themes in this Classical Chinese text and explain them in English: 庚寅，扩廓帖木儿攻兰州，指挥于光死之。
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On the day of gengyin, Kuoketuo Timur attacked Lanzhou, and the commander Yu Guang died in battle.
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