The Mushroom Kingdom

The Mushroom Kingdom is the main setting of the Super Mario franchise and Super Mario Bros: The Lost Brother. It is inhabited by the Toads, Goombas, and Koopas as well as many other species. Mario and his friends live in The Mushroom Kingdom, while Bowser and his ambitions threaten to take over, destroy, or otherwise hurt the kingdom. Princess Peach and Bowser both collectively rule certain parts of the kingdom, Peach owning places like Toad Town, Plack Beach or Bubble Lake, while Bowser owns places like DImble Wood, Quicksand Plateau and Darkworld. Although it is technically part of the kingdom, The Minus World is the kingdom during it's past.

Similarities to the Canon Kingdom
In The Lost Brother, the kingdom is to be mostly based on Mario and Luigi: Bowser Inside Story's areas, with areas like Plack Beach and Dimble Wood, though there are new places like The Fire Sea and Portal Island. Donkey Kong is present and other characters have ways in and out of the Mushroom Kingdom.