Haplogroup L3 is a human mitochondrial DNA (mtDNA) haplogroup.
Haplogroup L3 is confined to Africa and emigrant African populations. It is most common in East Africa.
However, L3 is also the haplogroup from which the macro-haplogroups M and N are believed to have arisen. These two haplogroups are ancestral to all haplogroups outside Africa, and are believed to represent the initial migration by modern humans out of Africa.
Spread of haplogroup L3. Image source
Spread of Haplogroup L3, from National Geographic