As of when I am posting this we still have no idea why these spawn, however they likely do spawn in vanilla several quadrillion blocks out and likely have something to do with the sheet farlands, the modulo "fartherer" lands or the strange effects you get if you set coordinate scale to a high value, likely the first. Meet the Shard Farlands, a strange float-related set of farlands that are unviewable in vanilla minecraft.
If you want to see these for yourself, decompile any version of Minecraft after infdev and make sure the farlands generate. Using eclipse, holding Ctrl+H replace all (double) with (float) and make sure you have Case Sensitive checked. If done correctly the game should recompile with little to no errors and teleporting to 392222 on X or Z or 196111 on both axis will bring you to the first iteration of the shard farlands.
However if you want to see why I mentioned high coordinate scale effects, teleport to 784400 in any or both directions and you should be greeted with what looks like a shattered variant of the normal farlands. At this moment we still do not know why these occur as they have only recently been found, other than they have to do with float precision loss, and that without the special patch they spawn farther than 53905378846979751 blocks out. If you want to see the sky variant, set height scale to 5,606,703.104, if using versions before 1.8 search for 684.412 using eclipse and replace the second value.
As of when I am posting this we still have no idea why these spawn, however they likely do spawn in vanilla several quadrillion blocks out and likely have something to do with the sheet farlands, the modulo "fartherer" lands or the strange effects you get if you set coordinate scale to a high value, likely the first. Meet the Shard Farlands, a strange float-related set of farlands that are unviewable in vanilla minecraft.
If you want to see these for yourself, decompile any version of Minecraft after infdev and make sure the farlands generate. Using eclipse, holding Ctrl+H replace all
(double)with(float)and make sure you have Case Sensitive checked. If done correctly the game should recompile with little to no errors and teleporting to 392222 on X or Z or 196111 on both axis will bring you to the first iteration of the shard farlands.However if you want to see why I mentioned high coordinate scale effects, teleport to 784400 in any or both directions and you should be greeted with what looks like a shattered variant of the normal farlands. At this moment we still do not know why these occur as they have only recently been found, other than they have to do with float precision loss, and that without the special patch they spawn farther than 53905378846979751 blocks out. If you want to see the sky variant, set height scale to 5,606,703.104, if using versions before 1.8 search for 684.412 using eclipse and replace the second value.
For anyone who doesn't use eclipse or who doesn't want to decompile Minecraft, here is a pre-made mod for release 1.12.