Polygonal volume collision?

Hi all,

I created a landscape for my game first chapter. I can’t allow the player to go everywhere he wants on it because if he climbs over a mountain very close to the border he’ll see that the landscape is limited rectangle and it’s not very pro !

I quicly painted on photoshop the dark parts (just to show you the idea) where i don’t want the player to go :

Can i set a kind of “collision polygonal volume” in Unreal Engine 4 to limit the freedom of movement of my character ?

Thanks