The Grand Duchy of Lithuania

For the Ukrainian lands, the Grand Duchy of Lithuania (1340—1569) was the era between Galicia-Volhynia and the Polish-Lithuanian Commonwealth. After the death of Yuri II Boleslav in 1340, Liubartas secured Volhynia, and his brother Algirdas advanced into the Siverian and Kyivan lands. In 1362 at the Battle of the Blue Waters, Algirdas crushed the Tatar emirs and liberated Kyiv, Podolia, and Volhynia — a pivotal moment in Ukrainian history. The Grand Duchy operated on the principle of "not to disturb the old, not to introduce the new" — preserving local elites, language, law, and church. The Union of Krewo in 1385 and the Union of Lublin in 1569 gradually transferred the Ukrainian lands under the Polish crown.