The grassland north of the Black Sea may be where horses were first tamed
A belt of grass nearly a million square kilometres wide runs from Bulgaria to Kazakhstan. Genetic studies point to it as the likeliest birthplace of the domesticated horse, and the leading theory in Indo-European studies places the speakers of the ancestral Proto-Indo-European language here too.
The Pontic–Caspian steppe covers some 994,000 square kilometres. It begins in northeastern Bulgaria and southeastern Romania, crosses Moldova and southern and eastern Ukraine, runs through the North Caucasus of southern Russia and reaches the Lower Volga on the Kazakh border. Forest steppe, a patchwork of grass and woodland, marks its northern edge; the Black Sea and the Crimean and Caucasus mountains mark the south. Near the Caspian a strip of dry lowland desert intervenes, and at the Ural-Caspian narrowing it merges with the Kazakh Steppe as part of the great Eurasian grassland.
The seas around it are leftovers. The Black, Caspian and Azov seas are remnants of the Turgai Sea, an arm of the ancient Paratethys that once covered much of what is now the West Siberian Plain. Biologists use the term Ponto-Caspian for the distinctive plants and animals native to these waters and plains. Historian Alex M. Feldman groups the steppe with the forests to its north as one historical region he calls Pontic-Caspian Eurasia.
Classical writers knew these lands as Cimmeria, Scythia and Sarmatia. For thousands of years they were home to mounted nomads, and many of those peoples went on to conquer settled lands in Europe, West Asia and South Asia. The Kurgan hypothesis links that mobility to language, proposing the steppe as the homeland from which Indo-European speech spread.
The roll of cultures with roots here is long. The farming Cucuteni-Trypillian culture flourished from 5300 to 2600 BCE; Sarmatians appear from the 5th century BCE; Magyar tribes, ancestors of the Hungarians, are attested from the 7th century CE; and the Bulgars gave rise to two Bulgarian empires. Later came Cossacks, Kalmyks, the Crimean Khanate and the Nogais.
Source: Pontic–Caspian steppe
