After the Union of Krewe in 1385, which loosely united the Kingdom of Poland and Grand Duchy of Lithuania, Poles and Lithuanians finally had the opportunity to develop their economies. A lucrative agricultural export market became the foundation for Poland's wealth and prosperity. Barges visited the grain warehouses erected along the Wisla, Vistula River, and transported the grain to Gdansk, where it was reloaded onto ships for transport across the Baltic Sea. Fortunes could be made, and lost, in the grain trade. This prosperous period was further augmented by the selection of the first elected Polish king at Kamien near Warsaw in 1569, the creation of the Polish-Lithuanian Commonwealth, and adoption of The Golden Liberty in 1573. This was Poland's Golden Age.
Alas, such prosperity did not go unnoticed by Poland's avaricous and imperialistic neighbors.