The origins of the first Cossacks are disputed, though the Constitution of Pylyp Orlyk claimed Khazar origin. The traditional post-imperial historiography dates the emergence of Cossacks to the 14th or 15th centuries, when two connected groups emerged, the Zaporozhian Sich of the Dnieper and the Don Cossack Host.
The Zaporizhian Sich were a vassal people of Poland–Lithuania during feudal times. Under increasing social and religious pressure from the Commonwealth, in the mid-17th century the Sich declared an independent Cossack Hetmanate, initiated by a rebellion under Bohdan Khmelnytsky. Afterwards, the Treaty of Pereyaslav brought most of the Ukrainian Cossack state under Russian rule. The Sich with its lands became an autonomous region under the Russian-Polish protectorate.
The Don Cossack Host, which had been established by the 16th century, allied with the Tsardom of Russia. Together they began a systematic conquest and colonisation of lands in order to secure the borders on the Volga, the whole of Siberia (see Yermak Timofeyevich), and the Yaik and the Terek Rivers. Cossack communities had developed along the latter two rivers well before the arrival of the Don Cossacks
Tags: ukraine kozaks, kozak, chivalry, kozak origin, historical ukrainian kozaks, yermak timofeyevich.