Neutral territories are not controlled by any player. They are represented by a gray color on the map.
Neutrals never attack, never get reinforcements, and can not move. However, the armies located on a neutral territory defend themselves in the same way that player-owned armies defend themselves.
It is possible for neutral territory to have more or less armies than it was defined in game settings, by either players playing blockade card, abandon card, or by a player surrendering or getting booted.