Druzhina

Druzhina, Drużyna or Družyna (Russian: Дружи́на; Ukrainian: Дружи́на, Druzhýna literally a "fellowship") in the medieval history of Poland and Kievan Rus' was a retinue in service of a chieftain, also called knyaz. The name is derived from the Slavic word drug (, pronounced droog) with the meaning of "companion, friend". Compare it to druhti of old Germanic cultures.

In early Rus a druzhina helped the prince administer his principality and constituted the area’s military force. The first members of a druzhina in Rus Khaganate were the Varangians, whose princes established control there in the 9th century. Soon members of the local Slavic aristocracy as well as adventurers of a variety of other nationalities became druzhinniki. The druzhina organization varied with time and survived in one form or another until the 16th century.

The druzhina was composed of two groups: the senior members, later known as boyars, and the junior members. The boyars were the prince’s closest advisers who also performed higher state functions. The junior members constituted the prince’s personal bodyguard and were common soldiers. Members were dependent upon their prince for financial support, but they served the prince freely and had the right to leave him and join the druzhina of another prince. As a result, a prince was inclined to seek the goodwill of his druzhina by paying the druzhinniki wages, sharing his war booty and taxes with them, and eventually rewarding the boyars with landed estates, complete with rights to tax and administer justice to the local population.

At the Battle of Lake Peipus the army of the Novgorod Republic had about 5000 men in all, and around 3000 men in both the cavalry and infantry were part of Alexander Nevsky's druzhina.

...
Wikipedia