Two cents:

1. I believe the Ottoman Empire was responsible for massacres against the Bulgarian people, not Turkey.

2. The textbook was obviously written by a Bulgarian (I worked with textbooks like that and directions in English were often bungled).

3. This example demonstrates how little interaction the every-day Bulgarian has with different ethnic groups (asian, african, etc.) It's an honest mistake of generalities that don't effect most Bulgarians.

4. It might be difficult for us Americans to understand this at first, but people around the world are going to see the world differently and their language is going to reflect that. That exercise might not be politically correct, but I'm certain there are examples in English that reveal a biased and discriminatory point of view (without us even knowing). One obvious example is the use of the word "Balkan" -- it's been used in many ways by Westerners to look down upon the people of southeastern Europe. Another one used often by Americans is the word "gypped" (actually, I'm not sure of the spelling) -- a common reference to getting cheated. Many Americans use that term not knowing it's a degrading reference to Gypsies.

It's better to discuss these issues with Bulgarians and ask questions than to get upset and make accusations about Bulgarians' attitudes toward race and ethnicity.