Darklands_1.5.1_v2.zip is a release file of the Minecraft resource pack Darklands Classic x32 Medieval Resource Pack, made for Minecraft 1.5.1. It was published on April 3, 2013 and is 7 MB in size. For the full description, screenshots and every other version, visit the Darklands Classic x32 Medieval Resource Pack resource pack page.
How to install: Put the .zip into .minecraft/resourcepacks (do not extract it) and enable it under Options → Resource Packs.