When Alice came visit Bella in NewMoon,Jake 発言しました he couldn't protect her because he was in"their land"he didn't want to break the treaty.when they left for volterra he said"i'll protect charlie screw the treaty"Why would any of that breakthe treaty?
Jacob technically broke the treaty in Twilight, によって telling Bella the story. Since both frequent the 白鳥, スワン house, it may be neutral ground, because of Bella.
Forks is a common land,it`s the Switzerland.Both Edward(vampires) and Jacob(werewolfs) can be here.I think Jake 発言しました that,like "Now YOUR ヴァンパイア come,so I can be near you,near them..." something like that,,,