The grass is always greener...
Ours generally stay within our land, about 4 acres, but they do love to be right near the fence to the neighbours. They sometimes go through but not for long. We also have wild junglefowl all over the place and they tend to chase our bantams away from their territory back into our piece. Funnily enough they rarely wander westward from their coop and it's about 80 metres from the boundary in that direction.
If you occaisionally sprinkle some food out for them, like rice or corn (banging the food tin while you do it) they quite quickly learn to come rushing back from wherever they are.
Your rooster is the one that determines where they go, get him trained to come back for food when he's near your boundary and he'll bring all but the most stubborn/headstrong girls back with him.