Board Thread:Warhammer 40k General Discussion/@comment-25222488-20151025234507/@comment-18016240-20151119005839

Careful with the language there Patton, you'll hurt the staff team's feelings and they'll remove the post.

Well, it is possible to travel outside of the galaxy but most races within it don't bother. In the Imperium's case it's because the Astronomicon's light (which is used as basically a psychic lighthouse that Navigators use to guide ships around) only reaches so far throughout the galaxy, if you travel beyond it's reach you're effectively flying blind when it comes to Warp travel. Along with that, most races aside from the Orks and maybe some Necrons and the odd isolated Eldar don't have any territory outside of the Milky Way and what they do have is very isolated.

Like Zixis pointed out it's just a theory, but if you check the Tyranids' lore, there's implications that they're running from something. GW being what it is, it hasn't said whether that's true or not or if we'll ever see this threat either because mysteries sell merchandise, they don't know what to add so they leave it blank, or some other explanation.