The unification of Lithuanian land began in the12nd century. Mindaugas, the first ruler of the Grand Duchy, was crowned Catholic Lithuanian King in 1253. This polytheistic country became the target of Teutonic Order and Livonia Order during the Northern Crusade. It was not until the late reign of Gediminas that this multi-ethnic and multi-religious country appeared and continued to expand under the leadership of his son alkire Das. Alkire Das's successor, Jogra, signed the Kreva Union in 1386, which left two strong marks in the history of the Grand Duchy of Lithuania: one was that Lithuania relied on Catholicism, and the other was the royal alliance between the Grand Duchy of Lithuania and the Kingdom of Poland (1385- 1569).

During the reign of Vitautas, the Grand Duchy was in the period of the greatest territorial expansion, and defeated the Teutonic Knights in the Battle of Granwad in 14 10. This period also marked the rise of Lithuanian aristocrats. After Tatas's death, Lithuanian relations with the Polish kingdom deteriorated extremely. Lithuanian nobles, including the Laziviu family, tried to undermine relations with Poland. However, the defeat of the Moscow-Lithuania war left the alliance unscathed.

1569 in July, Poland and Lithuania re-signed the treaty of alliance in lublin, stipulating that the two countries have a common parliament, a common system of selecting kings and a consistent foreign policy. Ukraine, which originally belonged to Lithuania, was directly incorporated into the territory of Poland, and the Grand Duchy of Lithuania retained its political independence and had its own government, laws, army and treasury. Historically known as the lublin merger. Since then, the two countries formally merged and established the Kingdom of Lithuania in Poland. 1at the end of the 6th century1at the beginning of the 7th century, Polish dignitaries tried to expand eastward and clashed with Russia. After a series of devastating wars, the Polish-Lithuanian Federation was carved up by the Russian Empire, Prussia and the Grand Duke of Austria in 1795 and perished.