ExtrabiomesXL

ExtrabiomesXL is a mod created by MisterFiber that adds many new biomes to Minecraft and creates much more biome diversity than in Vanilla Minecraft. This mod includes several new biomes, trees, blocks, and items to the game.

Important Note: Adding ExtraBiomesXL to Minecraft has one major con: Vanilla biomes become much more uncommon thus harder to find. To increase the probability of Vanilla biomes, a config file for ExtraBiomesXL allows you to disable certain biomes as you wish. You can also disable whether or not NPC Villages spawn in certain biomes.

Installing this mod also causes NPC Villages to generate in every biome in Minecraft although they seem to generate in more flatter regions over mountainous regions. As stated above village generation can be disabled for specific biomes via the ExtraBiomesXL config file.