During the 15th century, the population migrated and spread beyond the northern city wall into a newly formed self-governing precinct called New Town. The existing older settlement became eventually known as the Old Town. Both possessed their own town charter and independent councils. The aim of establishing a separate district was to accommodate new incomers or undesirables who were not permitted to settle in Old Town, particularly the Jews. Social and financial disparities between the classes in the two precincts led to a minor revolt in 1525. Following the sudden death of Janusz III and the extinction of the local ducal line, Masovia was incorporated into the Kingdom of Poland in 1526. Bona Sforza, wife of Sigismund I of Poland, was widely accused of poisoning the duke to uphold Polish rule over Warsaw.