In human genetics, Haplogroup B is a human mitochondrial DNA (mtDNA) haplogroup.
Haplogroup B is believed to have arisen in Asia some 50,000 years before present. Its ancestral haplogroup was Haplogroup R.
Haplogroup B is found throughout modern Asia. Its subgroup B2 is one of five haplogroups found in the indigeneous peoples of the Americas, the others being A, C, D, and X.
Since the migration to the Americas by the ancestors of Native Americans is generally believed to have been from Siberia, it is especially surprising that Haplogroup B is the only haplogroup found in Native Americans which is not found in modern North Siberian populations. Haplogroup B is found among Southern Siberians such as Tuvans and Buryat. This haplogroup is also found in Mongolians and population of Central China.
In his popular book The Seven Daughters of Eve, Bryan Sykes named the originator of this mtDNA haplogroup Ina.