Kaios!!

 

  The universe is split into 4 quadrants, the North Quadrant, the East quadrant, the West quadrant and the South Quadrant.  Each has it's own Kai.  Earth, Namek etc, are in the North Quadrant, which is ruled over by Kaio Samma (king Kai), or North Kai.  Ruling over all the universe and the 4 Kaios is the Grand Kai.  Grand Kai is said to be the most powerful being in the universe (but I mean, how many times have you heard that?-he is surpassed in strength by Goku, Pikkon, Buu, and probably Piccolo, Vegeta, Gohan and Mari no Trunks).  It is not known by many (only later in the series the Z team and the odd couple of people who may be fans of DBZ-not many), that everything in the universe is watched over by the Supreme Kai. The Supreme Kai is unbelievably powerful, but still needs Goku's help to defeat Buu.

 

This is how it would work for Earth, the most important first...

Supreme Kai_____Grand Kai_____North Kai_____King Yemma_____Kame/Dende_____Earth King