 The end of the eighteenth century saw the division of the Polish – Lithuanian Commonwealth , in three steps , among the neighboring states . The Kingdom of Prussia acquired Białystok and the surrounding region during the third partition . The city became the capital of the New East Prussia province in 1795 . Prussia lost the territory following Napoleon Bonaparte 's victory in the War of the Fourth Coalition as the resultant 1807 Treaties of Tilsit awarded the area to the Russian Empire , which organized the region into the Belostok Oblast , with the city as the regional center . 
