The Pontic–Caspian steppe, Pontic steppe, or Ukrainian steppe is the vast steppeland stretching from the northern shores of the Black Sea (called Euxeinos Pontos [Εὔξεινος Πόντος] in antiquity) as far east as the Caspian Sea, from Dobruja in the northeastern corner of Bulgaria and southeastern Romania, through Moldova and eastern Ukraine across Russian Northern Caucasus, Southern and lower Volga regions to western Kazakhstan, forming part of the larger Eurasian steppe, adjacent to the Kazakh steppe to the east. It is a part of the Palearctic temperate grasslands, savannas, and shrublands ecoregion of the temperate grasslands, savannas, and shrublands biome.

The area corresponds to Cimmeria, Scythia, and Sarmatia of classical antiquity. Across several millennia the steppe was used by numerous tribes of nomadic horsemen, many of which went on to conquer lands in the settled regions of Europe and in western and southern Asia.

The term Ponto-Caspian region is used in biogeography for plants and animals of these steppes, and animals from the Black, Caspian, and Azov seas. Genetic research has identified this region as the most probable place where horses were first domesticated.^[1]

According to a theory, called Kurgan hypothesis in Indo-European studies, the Pontic–Caspian steppe was the homeland of the speakers of the Proto-Indo-European language, and these same speakers were the original domesticators of the horse.^[2][3][4][5]

The Pontic steppe covers an area of 994,000 square kilometres (384,000 sq mi) of Europe, extending from Dobrudja in the northeastern corner of Bulgaria and southeastern Romania, across southern Moldova, Ukraine, through Russia to northwestern Kazakhstan to the Ural Mountains. The Pontic steppe is bounded by the East European forest-steppe to the north, a transitional zone of mixed grasslands and temperate broadleaf and mixed forests.

To the south, the Pontic steppe extends to the Black Sea, except the Crimean and western Caucasus mountains' border with the sea, where the Crimean Submediterranean forest complex defines the southern edge of the steppes. The steppe extends to the western shore of the Caspian Sea in the Dagestan region of Russia, but the drier Caspian lowland desert lies between the Pontic steppe and the northwestern and northern shores of the Caspian. The Kazakh Steppe bounds the Pontic steppe to the east.

The Ponto-Caspian seas are the remains of the Turgai Sea, an extension of the Paratethys which extended south and east of the Urals and covering much of today's West Siberian Plain in the Mesozoic and Cenozoic.