All of them originated in Africa and later migrated to Europe, Asia, Australia, &c.Asia, Africa and Europe, seeing as, scientifically, there are three distinct species of human: Caucasiod, Orientalis and Congoloid. Genetically, there is enough difference to separate them as such.
They are not separate species, any more than Siamese, grey tabbies and Manx's are different species of cat. There's just not that much genetic difference.
And where did you come up with this three race system? Why not a six or eleven race system? Why don't you include the San and Pygmy races, or the Polynesian, Melanesian, Negrito, Australian Aborigine or Inuit races? Some of them are a lot more genetically distinct than Caucasions vs Negroids.
Fact is, race is more a social construct than a biological reality. People are tribal. We never tire of creating out-groups and inventing underlying justifications for our categories.