[General] How to make a black area?

[Geshishouhu]

Hi guys, how to make a black area? Even by typing "iseedeadpeople", that area is still black (the area is not path-able and playable and no vision). I have seen at least two maps having this setting.
I also attached a screenshot to show what I mean. In the screenshot, the top left corner of the map is totally black.
Thanks all.

Edit: added one more screenshot with black areas.

 

[Boris_Spider]

I would assume that the Abyss tile-set (from Outland) is being used in conjunction with pathing blockers (to stop air units from traveling over the black regions).

"iseedeadpeople" reveals everything and can't be stopped that I know of (not directly).

//\\oo//\\

 

[Geshishouhu]

I would assume that the Abyss tile-set (from Outland) is being used in conjunction with pathing blockers (to stop air units from traveling over the black regions).

"iseedeadpeople" reveals everything and can't be stopped that I know of (not directly).

//\\oo//\\

I have checked that, but no...
Also, there is no vision in that area.

Edit: oops, I think u r right, it is Abyss.... Thanks.

 

[Veritas 117]

Is it just extra boundary that is added. You can find it next to the tileset on the terrain palette.