The Pontic-Caspian steppe, extending from the Danube estuary to the Ural mountains, has played a crucial part in European and Asian history. This is where the horse was domesticated, chariots invented, and one of the earliest place where the Bronze Age flourished and from which it expanded. From approximately 4000 BCE steppe people moved westwards to establish themselves around the Danube valley and the Carpathian basin, then little by little deeper into Europe. Here is a summary of this long series of migrations that is thought to have brought Indo-European languages an culture to Europe and contributed significantly to the modern European gene pool. You can visualize here the Bronze Age migrations .
- 4200-3900 BCE : Late Copper Age horse riders invade the old Balkanese tell settlements of eastern Romania and Bulgaria. Most of the towns and villages of the Gumelnita, Varna and Karanovo VI cultures are abandoned. A new hybrid culture emerge, the Suvorovo-Cernavoda culture (4000-3200 BCE), which will expand further south to the Aegean during the Ezero period (3300-2700 BCE).
- 3500 BCE : Other advances from the steppe into the Cucuteni-Tripolye culture lead to the formation of the hybrid Cotsofeni culture, also known as Usatovo culture, in north-eastern Romania.
- 3200-2800 BCE : First north-west expansion of the Yamna culture from the western steppe to modern Poland, Germany, Scandinavia and Baltic countries. Creation of the Corded-Ware (or Single Grave, or Battle-Axe) culture (3200-1800 BCE).
- 2800-2500 BCE : Hybrid people from the Cotsofeni and Ezero cultures start moving up the Danube and settle in mass in the Hungarian plain. The southward expansion of the Abashevo, Poltakva and Catacomb cultures from the Volga-Ural to the Black Sea shores pushed more pastoralists of the late Yamna culture to Europe.
- 2500-2300 BCE : Indo-Europeans expand from the Hungarian plain to Austria, Bohemia, Moravia, southern Poland and southern Germany and start the most important Central European Bronze Age culture : Unetice (or Aunjetitz).
- 2300-2000 BCE : The Indo-Europeans continue their advance to Western and Northern Europe, spreading the Bronze Age and the single grave tradition with them.
- 2000-1100 BCE : The Sea Peoples invade the Aegean and Eastern Mediterranean from the north (probably from the Black Sea). This is one of the most controversial part of ancient history due to the lack of clear evidence about the origin of the Sea Peoples. The Indo-Europeans from the steppe or from Europe itself were the only warriors with sufficiently advanced weapons and knowledge of seafaring to have destroyed the powerful palace-states of Greece, Anatolia, the Levant and Egypt. It also fits the 1000-year interval otherwise lacking any major migration from the steppes, at the time when the eastern Indo-Europeans were conquering Pakistan and India from Central Asia.
- 800-550 BCE : the Cimmerians are ousted from the Pontic steppe by their cousins the Scythians coming from the Volga-Ural region and Central Asia. The Cimmerians settle in Anatolia and around modern Romania around 800 BCE. The Cimmerian culture commenced circa 1200 BCE. Some archaeologists place their origins in the North Caucasus. Some accounts have it that the Cimmerians moved to northern Germany and the Netherlands and became the ancestors of some Germanic tribes, like the Sicambri (ancestors of the Franks). The Scythians followed between 650 and 550 BCE in Transylvania, Hungary and southern Slovakia. They kept trade routes with the steppes until the Roman conquest of Pannonia and Dacia.
- 100-500 CE : the Huns from southern Siberia invade Eastern Europe, pushing the Alans (a Samartian-descended tribe) westward. The Goths, Vandals, Franks, Angles, Saxons, Jutes and others cross into the Roman Empire under pressure from the new steppe migrants.
- 550-1000 CE : the next invaders from the steppe were the Avars, who entered the lower Danube region in 562. The Avars established their dominion over the Danube basin, from central Romania to eastern Austria, from the late 6th to early 9th century.
In the 4th century, some Bulgars had crossed the Caucasus into Armenia while others had already followed the Huns, then the Avars to Central Europe. The Pontic steppe and North Caucasus was ruled by the Bulgars during the Old Great Bulgaria period in the 7th century. Under pressure from the Khazars, the Bulgars split in two groups; one migrating north to Volga Bulgaria, and the other to the Carpathians founding the First Bulgarian Empire (680–1018 CE) around modern Romania and Bulgaria.
The Magyars and Khazars migrated from the Ural-Volga region to modern Ukraine around 830, raided their way across the Carpathians as far as Bavaria, where they were stopped in 956, then established themselves permanently in Hungary in the 10th century and founding the Kingdom of Hungary in 1001.
- 1350-1550 CE : the last people from Central Asia to come to Europe were the Turks, who conquered the Balkans from 1359 to 1481, then the Carpathians and Hungary from 1520 to 1566. They were not technically from the Pontic-Caspian steppe, but from areas of Central Asia settled over 4000 years ago by the Indo-Europeans from the Volga-Ural steppe. Like other Turkic peoples (Huns, Avars, Bulgars, Khazars, Tatars) the Turks supposedly brought a lot of R1a lineages with them (+ a little R1b).
Genetic impact
The continuous flow of steppe people had a cumulative effect on the European gene pool. The Copper and Bronze Age migrations are thought to have brought chiefly Y-haplogroup R1b1b2 (except the Corded-Ware expansion which originated in the forest-steppe and brought R1a1a) and mt-haplogroups U2, U3, U4, I, W to Europe, as well as other haplogroups that were there before like H, K, T, U5, V and X2.
The last presumably R1b people were the Cimmerians, who could have been R-U106/S21 based on the age and distribution of this subclade compared to the Cimmerian migration path. All subsequent migrations from the Scythians onwards would have brought Y-DNA R1a (as wel as some G1, G2a, N1c1 and Q).
South-East Europe now has the highest R1a diversity due to the numerous Eurasian tribes who settled there between 800 BCE and 1000 CE. Ancient DNA from the Scythians and more recent steppe people have confirmed that they belonged overwhelming to haplogroup R1a.