 Based on its disjunct distribution, O-K18 can be further divided into south subclade O1b1a1-PK4 and north subclade O1b1a2-PAGE59.O-PAGE59 is widely distributed in East Asia, whereas O-PK4 is more frequent in South China and Southeast Asia.O-PK4 is best known for the high frequency of its O-M95 subclade among populations of Southeast Asia and among speakers of Austroasiatic languages in South Asia.