What is "beastlands"

In the Dungeons & Dragons fantasy role-playing game, the Beastlands (more properly, the Wilderness of the Beastlands, formerly the Happy Hunting Grounds in early versions of the game) is a neutral (chaotic) good-aligned plane of existence. It is one of a number of alignment-based Outer Planes that form part of the standard Dungeons & Dragons (D&D) cosmology, used in the Greyhawk and Planescape campaign settings, as well as some editions of the Forgotten Realms setting.