Haplogroup R1b (R-M343), previously known as Hg1 and Eu18, is a human Y-chromosome haplogroup. It is the most frequently occurring paternal lineage in Western Europe, as well as some parts of Russia (e.g. the Bashkirs) and pockets of Central Africa (e.g. parts of Chad and among the Chadic-speaking minority ethnic groups of Cameroon). The clade is also present at lower frequencies throughout Eastern Europe, Western Asia, as well as parts of North Africa, South Asia and Central Asia. R1b has two primary branches: R1b1-L754 and R1b2-PH155. R1b1-L754 has two major subclades: R1b1a1b-M269, which predominates in Western Europe, and R1b1b-V88, which is today common in parts of Central Africa. The other branch, R1b2-PH155, is so rare and widely dispersed that it is difficult to draw any conclusions about its origins. It has been found in Bahrain, India, Nepal, Bhutan, Ladakh, Tajikistan, Turkey, and Western China. According to ancient DNA studies, most R1a and R1b lineages would have expanded from the Caspian Sea along with the Indo-European languages. Origin and dispersal The age of R1 was estimated by Tatiana Karafet et al. (2008) at between 12,500 and 25,700 BP, and most probably occurred about 18,500 years ago. Since the earliest known example has been dated at circa 14,000 BP, and belongs to R1b1 (R-L754), R1b must have arisen relatively soon after the emergence of R1. Early human remains found to carry R1b include: Villabruna 1 (individual I9030), a Western Hunter-Gatherer (WHG), found in an Epigravettian culture setting in the Cismon valley (modern Veneto, Italy), who lived circa 14000 BP and belonged to R1b1a. Several males of the Iron Gates Mesolithic in the Balkans buried between 11200 and 8200 BP carried R1b1a1a. These individuals were determined to be largely of WHG ancestry, with slight Eastern Hunter-Gatherer (EHG) admixture. Several males of the Mesolithic Kunda culture and Neolithic Narva culture buried in the Zvejnieki burial ground in modern-day Latvia c. 9500–6000 BP carried R1b1b. These individuals were determined to be largely of WHG ancestry, with slight EHG admixture. Several Mesolithic and Neolithic males buried at Deriivka and Vasil'evka in modern-day Ukraine c. 9500-7000 BP carried R1b1a. These individuals were largely of EHG ancestry, with significant WHG admixture. A WHG male buried at Ostrovul Corbuli, Romania c. 8700 BP carried R1b1c. A male buried at Lepenski Vir, Serbia c. 8200-7900 BP carried R1b1a. An EHG buried near Samara, Russia 7500 BP carried R1b1a1a. An Eneolithic