Keep mobs out of certain areas?

In my world, my spawn has an exit down into a village which is under siege by the zombie invasion. The problem is players can pull zombies from the village up into the spawn. Is there any plugin I can use to deny mobs from entering into certain areas? Here's a picture of what I am working with. The large building on the hill is spawn.



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EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Yes use World Guard!!

It requires World Edit as well. Look at a tutorial on youtube about world guard

For Use After You Learn World Guard:
Use /region flag [regionname] mob-spawning deny

Here is a list of all flags!
http://wiki.sk89q.com/wiki/WorldGuard/Regions/Flags

 

This flag will only stop mobs from spawning in the area, the issue is I want them to spawn in the village but not be able to enter spawn, or the stair area leading up to spawn.

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EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

They should despawn once they enter the region