The Jagiellonian Dynasty was a royal family that ruled over several Central and Eastern European countries from the late 14th to the 16th centuries. It originated with the marriage of Jogaila, the Grand Duke of Lithuania, to Queen Jadwiga of Poland in 1386, which united the two nations. The dynasty produced notable monarchs, including Casimir IV and Sigismund I, who strengthened the Polish-Lithuanian Commonwealth. The Jagiellonians played a significant role in European politics, fostering alliances and expanding their territories. Their reign is marked by cultural and economic growth, particularly during the Renaissance. The dynasty ended in 1572 with the death of Sigismund II Augustus, leading to the election of a new king.