Fun fact, if you stand on top of Peach's Castle in Mario Odyssey and look into the distance of the Mushroom Kingdom, you can see a desert, icy tundra, mountain range, dense forest and large body of water, representing the Worlds that Mario usually travels through in the 2D games
Fact: The Mushroom Kingdom is a country ruled by Princess Peach and the greater location of Peach's Castle.
Many races such as Toads and Goombas make their home there. The Mushroom Kingdom features a variety of environments and is known for its abundance of mushrooms.