पर्वतान्तर्द्वीपाश्च दुर्गा नाध्युष्यन्ते जनपदाभावात् ॥ कZ_०८.१.३१ ॥
parvatāntardvīpāśca durgā nādhyuṣyante janapadābhāvāt
山地要塞与岛屿要塞,在缺乏支撑的乡土(janapada)时,无法长期有人居住并维持。
Geography alone does not secure defense; a fort must be fed, staffed, and financed by a productive and connected hinterland.