Ancient Greek Fortifications 500–300 BC

As an agrarian-based society, the polis controlled and exploited a territory
(chora), which was delimited geographically by mountains or sea, or by proximity to another polis. The nearest and most powerful neighbour was the natural enemy. Border wars were thus common, as were inter-polis agreements and attempts to establish territorial rights over disputed areas. Autonomy was jealously guarded, but the necessities of collaboration made for a proliferation of foreign alliances, leagues of small communities, usually ethnically related, and hegemonies. There was also constant interchange and competition between poleis, so that despite their separate identities a common culture was always maintained.