which region does the a blood come from
In Europe, only two areas with a high rate of blood group B appear: one among the group of non-Indo-European peoples known as the Finno-Ugrics (such as the Hungarians and the Finns), the other among the central Slavic peoples (Czechs, Southern Poles, and Northern Serbs).
The A allele apparently was absent among Central and South American Indians. Distribution of the A type blood allele in native populations of the world. The O blood type (usually resulting from the absence of both A and B alleles) is very common around the world. About 63% of humans share it. Type O is particularly high in frequency among the indigenous populations of Central and South America, where it approaches 100%.
There is a very high incidence of AB blood in subcontinental Indians, again probably the result of migration, conquest, caste distinctions and intermingling . Little evidence for the occurrence of group AB extends beyond 900 to 1,000 years ago, when a large western migration of Eastern peoples took place.
Interestingly, among the Asiatics, they and the Japanese are the only areas that show high frequencies of blood group A as well. The northern Chinese and Koreans have high rates of blood group B, and lower rates of blood group A. Nowadays, blood group B accounts for about ten percent of the world's population.