Jadwiga of Poland
On 12 December 1385, few months after the Union of Krewo, Siemowit IV, Duke of Masovia, reached a compromise with king Jadwiga of Poland and her intended consort king Jogaila (Władysław II Jagiełło), brother of Alexandra. Siemowit IV agreed to cease his rival claims to the Kingdom of Poland, pay homage to Jadwiga and Jogaila, and to assume position of a hereditary vassal to the Polish Crown in exchange for 10,000 Prague groschen and fief Duchy of Belz. The agreement was solidified by marriage of Siemowit IV and Alexandra in 1387.