This article is from the 2006 series of SMBZ and is no longer canon.
The Mushroom Kingdom is one of the largest kingdoms of Mushroom World and is the home of Mario, Luigi, Yoshi, Princess Peach, and many of their friends. Most of Super Mario Bros. Z takes place in the Mushroom Kingdom.The Mushroom Kingdom is a part of the Mushroom World, to the northeast of the Beanbean Kingdom and north of Yoshi's Island.
Most of the inhabitants are toads, however more species appear from several RPGs and spin-offs.
The Kingdom's currency is the coin, however, one Mushroom Kingdom coin is worth a fraction of a Bean Bean coin. It is unknown how a Mushroom Kingdom coin translates into a Diamond City dollar or any other Mario currency.
Princess Peach Toadstool is the current ruler of the land, but it has fallen under the control of other characters (usually villains) throughout the series.
In Super Mario Bros. Z, the Mushroom Kingdom is the primary location. As of Episode 7 the only other locations the heroes have visited are Yoshi's Island and the Minus World. The Mushroom Kingdom in the series is always treated as the whole world of Mario instead of mentioning the Mushroom World is another world parallel to Mobius and Earth.