Refined phylogenetic tree of Haplogroup O-M134, and the frequency of its sub-haplogroups genotyped in this study. ‘East' refers to the samples origins from the provinces of Jiangsu, Zhejiang, Anhui and Shanghai. ‘South' refers to provinces of Guangdong, Hunan, Hubei and Fujian. ‘North' refers to provinces of Hebei, Henan, Shandong, Shanxi, Tianjin and Beijing. ‘Northwest' refers to provinces of Shaanxi and Gansu. ‘Southwest' refers to Guizhou, Sichuan and Chongqing. ‘Northeast' refers to provinces of Jilin, Heilongjiang and Inner Mongolia.