Regiment or the Regimental system (Ukrainian: Полк, romanized: Polk, Ukrainian: Полковий устрій, romanized: Polkovyi ustriy) is a historical administrative, territorial, military and judicial unit of the country's subdivision of the Cossack Hetmanate and the Sloboda Ukraine in the XVII–XVIII centuries.[1]
System was expanded out of already existing system of the Registered Cossacks over Kyiv, Bratslav and Chernihiv Voivodeships in the Polish–Lithuanian Commonwealth.
Regiments were headed by the Cossack Colonel (Ukrainian: Полковник, romanized: Polkovnyk) who was a member of the Cossack Council of the Officers (Ukrainian: Рада Старшин, romanized: Rada Starshyn).
Regiment was the first level of the administrative and military division of the Cossack Hetmanate.
In 1649, when the Cossack Hetmanate was established by the Treaty of Zboriv and controlled both the right and left banks, it included 16 regiments. After the loss of the Right–Bank Ukraine, a number was reduced to 10 regiments.