Francisco Bethencourt. Racisms.

A controversially argued, but altogether great book. He traces beginnings of the racial (bloodline-based) persecution of Jews in Iberia as a beginning of modern racism. Here, I must digress. For all of the human history the stranger being from another village was a sufficient reason to hit his head by a hard rock. Only when this reasoning started to be challenged, "racism" appeared (witticism of one Belgian historian).
            A beginning of colonial expansion induced application of racial criteria from the peoples on the bottom of European ethnic pile--stateless Jews, Gypsies but also Finns, Latvians, etc. because the existence of the national state was the prima facie of civilization--to colonized peoples. Yet, in "natural" classifications of XVIII century (Linnaeus, Buffon, De  Pauw) race is largely equated with geography in a fashion of a geographic map (whites--Europeans, yellow or brown races--Asians, red--Americans and black--Africans).
            Only in mid-19 century Englishman Knox in "A philosophical inquiry on the influence of race over the destiny of nations" invented racial classification from the highest (Anglo-Saxon) to the lowest (Bushmen, Hottentots and Gypsies). Yet, Knox was against European colonialism, which he saw as a dilution of the white race.
            All in all, in XX century, racism was repugnant. In XXI century, in view of modern genetics and linguistic studies, it is simply ridiculous. Yet, many policies are still in thrall of this garbage indicating the rise of the early modern nation state.