Established under a native dynasty as a fairly typical medieval kingdom, Poland was gradually transformed into a "republic of nobles" whose institutions foreshadowed many later political developments, in particular the Solidarity movement of the 1980s. Drawing on early Polish chronicles as well as more recent works, we will explore how the early Polish state became established in the 10th century, then nearly disintegrated in succeeding centuries before reaching its medieval apogee under King Casimir the Great in the 14th century. Following the extinction of the original Polish dynasty, the country was ruled by elected Kings—sometimes well and sometimes badly. In 1386, Jagwiga of Anjou, who had been elected "King" of Poland a few years earlier, married Jogaila, Grand Duke of Lithuania. During the era of the resulting Jagiellonian dynasty, the combined state of Poland-Lithuania became the largest in Europe outside of Russia. Polish and Lithuanian aristocrats became some of the wealthiest in Europe, overseeing vast estates producing grain to be supplied to Western Europe through the important port of Danzig, on the Baltic Sea.