Kautilya's Arthashastra 8.1.32

8.1.32

karṣakaprāye tu durgavyasanam, āyudhīyaprāye tu janapade janapadavyasanam iti //

No, says Kautilya, for forts, finance, and the army depend upon the people; likewise buildings, trade, agricu1ture, cattle-rearing, bravery, stability, power, and abundance (of things). In countries inhabited by people, there are mountains and islands (as natural forts); in the absence of an expansive country, forts are resorted to. When a country consists purely of cultivators, troubles due to the absence of fortifications (are apparent); while in a country which consists purely of warlike people, troubles that may appear are due to the absence of (an expansive and cultivated) territory.