The article presents the events that happened in 1598, when a 'wanton drove o people' led by a Mr. Brzozka raided and plundered the Bialystok estates. This episode is one of the oldest documented information about the history of Bialystok during the Wiesiolowski family reign. In the light of the account relating to this event, a village called Bialystok was located within the territory of the Grand Duchy of Lithuania. This information indicates that the Polish-Lithuanian border was of a relatively unstable character. It can be confirmed by numerous border commissions appointed by the Sejm in the 16th and 17th centuries, whose aim was to permanently demarcate Podlasie from the Grand Duchy of Lithuania. Krzysztof Radziwil's actions, who called for the Tartars to crush the 'Brzozka gang', prove the effectiveness of this military group formation, which could promptly be sent for to provide services assuring domestic security.