The origins of the first Cossacks are disputed. Traditional
historiography dates the emergence of Cossacks to the 14th to 15th centuries. Towards the end of the 15th century, the Ukrainian Cossacks formed the
Zaporozhian Sich centered on the fortified Dnipro islands. Initially a vassal of
Polish–Lithuanian Commonwealth, the increasing social and religious pressure from the Commonwealth sparked a series of uprisings, and the proclamation of an independent
Cossack Hetmanate, culminating in a
rebellion under
Bohdan Khmelnytsky in the mid-17th century. While the Cossacks were useful to the Polish-Lithuanian states in the war periods, they proved to be more problematic in the peacetime, due to their
raids on the Commonwealth neighbours (primarily, the
Ottoman Empire and its allies). Further, the
Polish nobility tried to assert control over the Cossack territories, turn them into
feudal latifundia, limit the growth of the militant Cossacks, and even reverse it, by turning the Cossacks into
serfs. Afterward the Khmelnytsky Uprising, the
Treaty of Pereyaslav brought most of the Cossack Hetmanate under Russian control. The Zaporozhian Cossacks were not the only notable group of Cossacks; others included the
Don Cossack Host,
Sloboda Cossacks,
Terek Cossacks and
Yaik Cossacks. As the
Tsardom of Muscovy took over the disputed Cossack lands from Poland–Lithuania, all Cossacks eventually came under Russian rule, but the Tsarist and later Imperial government had only a limited degree of control over them. The Cossacks provided refuge for runaway serfs and bandits, and often mounted unauthorized raids and pirate expeditions against the
Ottoman Empire. While the Cossack hosts in the
Russian Empire served as buffer zones on its borders, the expansionist ambitions of the empire relied on ensuring control over the Cossacks, which caused tension with their traditional independent lifestyle. As the empire attempted to limit Cossack autonomy in the 17th and 18th centuries, this resulted in rebellions, such as those led by
Stenka Razin,
Kondraty Bulavin and
Yemelyan Pugachev. In extreme cases, whole Hosts could be dissolved, as was the fate of the
Zaporozhian Sich in 1775. In this last phase of their history, the Cossacks lost most of their autonomy to the Russian state. Cossack uprisings, like the Cossack people themselves, have been portrayed variously in the Polish,
Russian and
Ukrainian historiographers. == List of uprisings ==