Minecraft wiki entry for After_Beta_1.8, associated text: On the Y-axis, the Far Lands initiate at around twice the former number, which is therefore ±25,101,648. Since blocks cannot exist above y=320 or below y=-64 in the vanilla game, to observe the Far Lands in their natural place, mods such as the Cubic Chunks mod must be used to allow terrain to generate in such positions.