Voyi

The voyi (singular voi or voy) formed a category of armed forces in ancient Rus'.

Military History of Ukraine
Kievan Rus'
Druzhyna (862–1240)
Kingdom of Galicia–Volhynia
Voyi
Polish–Lithuanian Commonwealth
Registered Cossacks Zaporozhian Cossacks (1492–1648)
Zaporizhian Host
Zaporozhian Cossacks (1648–1775)
Austria-Hungary
Legion of Sich Riflemen (1914–1918)
Ukrainian People's Republic
Ukrainian People's Army (1917–21) Sich Riflemen (1917–21) Ukrainian Galician Army (1918–19)
Free Territory
Revolutionary Insurrectionary Army (1918–1921)
Carpathian Ukraine
Carpathian Sich (1938-39)
Ukrainian People's Republic in exile
Sich Regiment of Horlis-Horskyi (1939-40) Polissia Sich (1941-42)
Ukrainian National Government
UPRA (1941–1944) Ukrainian Insurgent Army (1941–1955)
Ukrainian SSR / Soviet Union
Red Cossacks Ukrainian Soviet Army (1918–19) none (1919–1991), part of the Soviet Armed Forces
Ukraine
Armed Forces (1992–Present)

Armies of Russia
Kievan Rus'
Druzhina 862–1283 Voyi
Grand Duchy of Moscow
Landed Army 1482–c. 1700
Tsardom of Russia
Streltsy c. 1550–1721 New Order Regiments 1648–98
Russian Empire
Imperial Russian Army 1721–1917
Russian Republic
Russian Army 1917 People's Army 1918
Russian State
White Army 1918–23
Russian SFSR / Soviet Union
Workers' and Peasants' Red Army 1918–46 Soviet Army 1946–92
Russian Federation
Russian Ground Forces 1992–present

Unlike the standing force (the druzhina), the voi force was drafted from a local population. Alongside the druzhina, the voyi formed a basis of an army in Rus'. A prince (knyaz) would appoint a voivode (from voi - "army", and vode - "to lead", meaning "warlord") to command them.