Haplogroup O-M122 (also known as Haplogroup O2 (formerly Haplogroup O3)) is an Eastern Eurasian Y-chromosome haplogroup. The lineage ranges across Southeast Asia and East Asia, where it dominates the paternal lineages with extremely high frequencies. It is also significantly present in Central Asia, especially among the Naiman tribe of Kazakhs. This lineage is a descendant haplogroup of haplogroup O-M175.