Grass Land is one of the constituent nations of the Mushroom World, ruled by Grass Land's King. It is located to the south of Jewelry Land, the east of the Mushroom Kingdom and Koopa Kingdom, the north of Desert Hill, and the west of the Pipe Maze.
The geography of Grass Land is quite similar to that of the Mushroom Kingdom, having cylindrical hills topped by a dome. Unlike the Mushroom Kingdom, these hills are all one color (green), and have quite simplistic patterns with eyes. The area of Grass Land around 1-5 has rocky terrain. The rest of the kingdom has either dried grass or live grass as the main terrain, often with gentle hills or Bolted Blocks. There are few known Grass Land settlements. Grass Land Castle is the capital, as well as the home of the King, and there are a few other scattered buildings.
Grass Land was invaded by Bowser during the events of Super Mario Bros. 3. Larry Koopa was the main attacking force here, with a base of operations in his airship. Larry stole the King's Magic Wand and turned him into a Cobrat. Mario, at the behest of Princess Peach, went out to save Grass Land and its king. Grass Land was the first country of the Mushroom World that Mario explored; after finishing here, Mario moved on to Desert Hill.