Board Game Arena

Why are some regions marked as controlled even though there are no army units present? If I move in a unit to flip control, but later move out, will I retain area control? Or is there some default setting for each space?

At the start of the game, spaces are set up controlled by each faction, but if you take it and move out you'll retain control.

"Whenever one of your infantry or tanks occupies a land space, you take control of the space. You continue to control the space, even if your piece is no longer there, until an enemy piece occupies the space.