Regarding Tom Mungall's discussion of race:
Check some modern anthropology textbooks such as _Human Biology and
Behavior_ by M.L. Weiss and A.L. Mann. Anthropologists have done most of
the studies of human variability and have found that race is not a useful
concept. Instead they prefer to use the word 'cline' which refers to the
distribution of a specific trait. Clines for distributions of different
traits can have overlapping boundaries and exhibit continuous gradations.
When you talk about population movements, you should realize that human
populations have always been moving and mixing. In historic times, think
of all the invasions of Asians into Europe - Huns, Alans, Magyars,
Bulgars, Turks etc. The Romans settled Sarmatian auxiliaries along
Hadrian's wall and the Mongols settled Sarmatians on China's Pacific coast.
Just because you happen to have blue-eyed genes from some northern
European ancestors doesn't mean you don't also have genes for toenail
thickness or something from a Hun.
Race is a culturally created concept.
SUNY at Buffalo