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 Jogaila, the Grand Duke of Lithuania, who became King of Poland in 1386 through his marriage to Queen Jadwiga. This union marked the beginning of a powerful dynasty that significantly influenced the region's politics and culture. The dynasty produced notable monarchs, including Casimir IV and Sigismund I, who expanded the territories of the Polish-Lithuanian Commonwealth. The Jagiellonians are remembered for their contributions to the arts, education, and the strengthening of the state, leaving a lasting legacy in Polish and Lithuanian history.