《水经注·卷二十》
魏征讨仇池时，修筑此城驻防。故道水与马鞍山水汇合。
西南径故道城东，魏征仇池，筑以置戍。与马鞍山水合。
When Wei Zheng was fighting Qiu Chi, he built this city for defense. Gu Dao Shui and Ma An Shan Shui converge.
<s>[INST] Kindly elucidate the central themes in this passage in English: 西南径故道城东，魏征仇池，筑以置戍。与马鞍山水合。 [/INST] When Wei Zheng was fighting Qiu Chi, he built this city for defense. Gu Dao Shui and Ma An Shan Shui converge.</s>
Kindly elucidate the central themes in this passage in English: 西南径故道城东，魏征仇池，筑以置戍。与马鞍山水合。
user
When Wei Zheng was fighting Qiu Chi, he built this city for defense. Gu Dao Shui and Ma An Shan Shui converge.
assistant