Сигизмунд Кейстутович
From surviving documentation we know that around 1437, a representative of the family Raczków, Jakub Tabutowicz with the coat of arms of Łabędź, received from Michael Žygimantaitis son of Sigismund Kęstutaitis, Duke of Lithuania, a wilderness area located along the river Biała that marked the beginning of Białystok as a settlement. Białystok administratively was part of the Podlaskie Voivodeship, after 1569 also part of the Lesser Poland Province of the Crown of the Kingdom of Poland.