There were two views of how a polis was formed. The first was military: a scattered group of people came to live in one city behind a set of protective walls. The other was political: a group of people agreed to live under one authority, with or whithout the protection of a walled city. Synoikismos, or 'Living together', embraces both. Any political entity implies a population that recognizes a common authority, but the first 'city-states' were not always based on a city. Sparta makes the point. We think of Sparta as a city, but the Spartans were proud of the fact that they lived in villages without protective walls: their army was their wall and 'every man a brick.
