@mdmartin101:
Then what was the purpose of the Kaioshin's?
According to Daizenshuu 7 and the Super Exciting Guides, the regular Kaios only watch over the living world, while the Kaioshins watch over both the living world and afterlife. That's why the Kaioshin Realm is located outside of the giant ball that contains the DB afterlife and living world, and revolves around it like a moon. This also explains the Kaioshins' name: "Gods of the World Kings". They're gods not only of the ordinary mortals, but also of the other gods like the regular Kaios. Piccolo refers to the East Kaioshin as "god of the gods" at one point in the manga.
Also, in the Super Exciting Guide: Character Volume, Toriyama says that Kaios and Kaioshins are selected by lottery from among the members of a special race called the Shinjin ("Fruit Pit People", more or less), so called because they are born from the fruit of the "World Tree". Shinjin born from regular World Tree fruit are eligible to become Kaios, while only those Shinjin born from rare golden fruit can become Kaioshins. So the split between Kaios and Kaioshins reflects this natural split in the Shinjin race.