The black/white/mongoloid breakdown is a very rough separation. Among blacks, look at variations of sub-Saharan people: the tall Watusi, the pygmies, the lighter-skinned Khoikhoi, the darker-skinned Bantu, the Somali -- there's a lot of variation there. Similarly among Caucasians you have the fair-skinned red haired Irish versus the dark-skinned people of India, and variations in between. Among mongoloids you have Japanese, Polynesian, American Indian, etc. From one way of looking at it, there are dozens or hundreds of races.
The way I still see it though, there are sub-races within the three primary races. I understand that. My original contention was there were just the three races: Negroid, Caucasoid and Mongoloid. From them came all the others. It had to have started out at some time with those three distinct races.