I know what your thinking of: The Farlands. I have found another lands called the corner crosslands. The crosslands also exists as strips of land 1 block skinny and completely flat. Mobs fall through, certain blocks get warped, and you can look inside blocks! You can only move up, down, and look around.

To Reproduce: Go into a flat world and teleport to 9999999999 10 99999999999

What should happen: I dont know

What happens: You teleport into the corner crosslands.

For more info watch Kunai's video on youtube about the crosslands. (Btw my sister(GiannaParrotAWK), and I (RoccoMG2) found this place first.)