>>713890567
The Koronus Expanse was on the wrong side of it from where Terra/Earth is in the galaxy, and its main entrance was sandwiched between two massive warpstorms that are temperamental on a good day. See the Calixis Sector/Halo Stars in the top left? The Expanse is in there.
And that's before Cadia exploded and the galaxy cracked in half.
There's a reason why trying to leave the map causes the warp to mulch your ship.