unknown
unknown region
terra incognita

And on, to the wild, unknown regions of space beyond.

Were his two companions thinking of their trip through those unknown regions?

There is no other way into the unknown region.

I would just as soon emigrate now to regions unknown, in another world.

Maybe from there it would be possible to see beyond the city, into the Unknown Regions.

Even with the stars out, it was difficult to travel unknown regions by starlight alone.

They had pushed, as I have said, into the still unknown regions of the West.

She had heard tales of people who tried to go out into the Unknown Regions.

He teleports her to an unknown region of space.

They all leave their current posts and travel into the Unknown Regions.