《资治通鉴·汉纪·汉纪三十八》
此前，莎车认为汉朝不会出兵，便向龟兹投降，疏勒都尉番辰也背叛了汉朝。
先是莎车以为汉兵不出，遂降于龟兹，而疏勒都尉番辰亦叛。
Before this, Shache, thinking that the Han Dynasty would not send troops, surrendered to Kucha, and Fan Chen, the governor of Shule, also betrayed the Han Dynasty.
<s>[INST] Kindly elucidate the central themes in this passage in English: 先是莎车以为汉兵不出，遂降于龟兹，而疏勒都尉番辰亦叛。 [/INST] Before this, Shache, thinking that the Han Dynasty would not send troops, surrendered to Kucha, and Fan Chen, the governor of Shule, also betrayed the Han Dynasty.</s>
Kindly elucidate the central themes in this passage in English: 先是莎车以为汉兵不出，遂降于龟兹，而疏勒都尉番辰亦叛。
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Before this, Shache, thinking that the Han Dynasty would not send troops, surrendered to Kucha, and Fan Chen, the governor of Shule, also betrayed the Han Dynasty.
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