In the 15th century, the Cossack society was described as a loose federation of independent communities, often forming local armies, entirely independent from the neighbouring states (of, for example, Poland, the Grand Duchy of Moscow or the Khanate of Crimea).
Hrushevsky states that Cossacks could have descended from the long forgotten Antes, or groups from the Berlad territory in present-day Romania, then a part of the Grand Duchy of Halych, Brodniki.
The Zaporozhian Cossacks lived on the Pontic-Caspian steppe below the Dnieper Rapids (Ukrainian: za porohamy), also known as the Wild Fields.
They became a well-known group whose numbers increased greatly between the 15th and 17th centuries.
In 1261 some Slavic people living in the area between the Dniester and the Volga were mentioned in Ruthenian chronicles.
It is not clear when new Slavic people apart from Brodnici and Berladniki started settling in the lower reaches of major rivers such as the Don and the Dnieper after the demise of the Khazar state.
Cossack communities had developed along the latter two rivers well before the arrival of the Don Cossacks.
By the 18th century, Cossack hosts in the Russian Empire occupied effective buffer zones on its borders.
However, Slavic settlements in Southern Ukraine started to appear relatively early during the Cuman rule, with the earliest ones, like Oleshky, dating back to the 11th century.
Early "Proto-Cossack" groups are generally reported to have come into existence within the present-day Ukraine in the mid-13th century as the influence of Cumans grew weak though some have ascribed their origins to as early as the tenth century.Cossacks were usually organized by Ruthenian boyars or princes of the nobility, especially various Lithuanian starostas.