Minecraft wiki entry for The_Update_that_Changed_the_World, associated text: Development began two months after 1.6.2 was released. Fourteen development snapshots were released, from 13w36a to 13w43a. Several iterations of the launcher were released during this time period, from 1.2.3 to 1.2.8. Also during the development period, 1.6.4 was released. Nearer the end of the snapshot cycle for the 1.7.2 update, Mojang focused primarily on fixing bugs, rather than adding new features.