R1a people appear to have been the first to penetrate into Europe, with the Corded Ware (Battle Axe) culture (3200-1800 BCE) as a natural western expansion of the Yamna culture. They went as far west as Germany and Scandinavia. DNA analysis from the Corded Ware culture site of Eulau confirms the presence of R1a (but not R1b) in central Germany around 2600 BC

Haplogroup R1a (Y-DNA)

R1a (distribution map) is thought to have been the dominant haplogroup among the Indo-European speakers who evolved into the Indo-Iranian, Mycenaean Greek, Macedonian, Thracian, Baltic and Slavic branches.

The most likely origin of the Proto-Indo-Europeans lies in the Kurgan culture (7000-3000 BCE) and the subsequent Yamna culture (3500-2200 BCE), between modern Ukraine and south-west Russia. Their expansion is linked to the domestication of horses in the Eurasian steppes, and the invention of the chariot (see R1b above).

The western branch

The first expansion of R1a took place with the westward diffusion of the Corded Ware (or Battle Axe) culture (3200-1800 BCE) from the Yamna homeland. This resulted in R1a being the dominant haplogroup in the northern half of Eastern Europe nowadays, like in Poland (56% of the population), Ukraine (50%), Belarus (45%), Russia (40%), Slovakia (40%), Latvia (40%), Lithuania (38%) and the Czech Republic (34%)

The Germanic branch of Indo-European languages probably inherited more from the R1b cultures, although R1a is likely to have arrived earlier in Scandinavia, during the Corded Ware period. R1a people would have mixed with the pre-Germanic I1 aborigines to create the Nordic Bronze Age (1800-500 BCE). R1b would have reached Scandinavia later as a northward migration from the contemporary Hallstatt culture (1200-500 BCE). The first truly Germanic tongue could have been a blend of Hallstatt Proto-Celtic and the Corded-Ware Proto-Slavic with a few pre-Germanic loan words. The fact that present-day Scandinavia is composed of roughly 40% of I1, 20% of R1a and 40% of R1b reinforces the idea that Germanic ethnicity and language had acquired a tri-hybrid character by the Iron Age.

The Corded Ware culture was followed by the Trzciniec culture (1700-1200 BCE) and the Lusatian culture (1300-500 BCE) in modern Balto-Slavic countries.

Historically, no other part of Europe was invaded a higher number of times by R1a steppe peoples than the Balkans. Chronologically, the first R1a invaders came with the westward expansion of the Corded Ware culture (from about 3200 BCE), then the Mycenaean invasion (1600 BCE), followed by the Thracians (1500 BCE), the Illyrians (around 1200 BCE), the Huns and the Alans (400 CE), the Avars, the Bulgars and the Serbs (all around 600 CE), and the Magyars (900 CE), among others. These peoples originated from different parts of the Eurasian steppes, anywhere between Eastern Europe and Central Asia, which is why such high STR diversity is found within Balkanic R1a nowadays. It is not yet possible to determine the ethnic origin for each variety of R1a, apart from the fact that about any R1a is associated with tribes from Eurasian steppe at one point in history.

The eastern branch

The eastern branch of the R1a steppe people was the Andronovo culture (2300-1000 BCE), around modern Kazakhstan, which correspond to the Indo-Iranian branch of languages. Their migration to the south have resulted in high R1a frequencies in southern Central Asia, Iran and the Indian subcontinent. The highest frequency of R1a (about 65%) is reached in a cluster around Kyrgyzstan, Tajikistan and northern Afghanistan. In India, 15 to 45% of the population is R1a, depending on the region and caste. Over 70% of the Brahmins (highest caste in Hindusim) belong to R1a1, due to a founder effect.

Distribution of haplogroup R1a in Eurasia

Distribution of haplogroup R1a in Eurasia