Haplogroup BT (Y-DNA)
Haplogroup BT (Y-DNA) descends from Haplogroup Y (Y-DNA) and split off from Haplogroup A (Y-DNA) in North East Africa approximately 55,000 years ago. It is the parent Haplogroup of all modern Y-DNA Haplogroups except for A. It has two haplogroups descended from it:
Previously known as Haplogroup BR (Y-DNA) and Haplogroup YxA (Y-DNA).