The Grand Duchy of Lithuania began to take shape during a period of significant changes in the foreign policy environment.
During the formation of the state, the huge territory of Russia was conquered by the Mongol-Tatars. This fact was favorable, since the Grand Duchy of Lithuania was thus protected from invasion from the east for the next century.
From the second half of the 12th century, Lithuanians were divided into two ethnic groups. Upper Lithuania (aukstaite) was attributed to the first, lower and “Zhmud” (squeeze) to the second.
It should be noted that the Lithuanians were at a lower level in political development than the East Slavic peoples. Gradually, the Lithuanian princes in some Russian cities established themselves on the tables. After Mindovg (Prince of Lithuania) destroys his opponents, there is a "centralization". During this period, the core of the new state begins to form. The Grand Duchy of Lithuania and Russia continues to develop under the successors of Prince Mindovg, in particular during the reign of Gediminas. When he reigned, the territory of upper Lithuania, as well as the territories of Black Russia (Ponemanye) attached to them, became part of the state. The Grand Duchy of Lithuania annexed part of the Turovo-Pinsk and Polotsk lands.
The capital of the state for a certain period was located on Russian territory in the city of Novgorod Lithuanian. Then she was transferred to Vilna.
The formation of a new state, which was started by the first great princes of Lithuania (Gedimin and Mindovg), was followed by Keistut and Olgerd. Between them were divided functions. So, the country's defense from the knights lay on the shoulders of Keistut, Olgerd was engaged in the seizure of Russian territories. As a result, the Grand Duchy of Lithuania annexed Kiev, Polotsk, Volyn, Chernihiv-Seversky territories, as well as Podillia. Old Russian lands at the same time had an autonomous status.
At the end of the 14th century, the dynasty of rulers was suppressed in the Polish state. The daughter of Louis Jadwig ascended the Polish throne. After the coronation, a marriage was concluded between Jadwiga and Jagiello (the heir to Olgerd).
After the wedding of Jagiello and Jadwig in 1385, the Union of Krev (Union of Lithuania and Poland) was signed. In addition, Lithuania was baptized pagan in the Catholic faith. This led to a weakening of the Orthodox faith and the elimination of the pagan religion.
The period of 14-15 centuries was also marked by the internal confrontation of the clan branches formed by the sons of Olgerd and Keistut. As a result, the Grand Duchy of Lithuania was divided into spheres of influence. Vytautas (son of Keystut) reigned in Lithuania.
According to historians, this period was the heyday of the state.
After the death of Vitovt, the era of decline in the history of Lithuania began.
In 1413, the Gorodel Union was concluded . With its signing, the process of polonization of the principality and the spread of Catholicism begins. In addition, with the conclusion of the Union of Gorodel, prerequisites began for the offensive of Poland on the Russian territories of the Grand Duchy.
The conditions that were created in the state contributed to the outbreak of war. In historical sources, it is called the "uprising of Svidrigailo" (the son of Olgerd). Lithuania split into two parts. Sigismund (the son of Keistut) sat in Lithuania. Svidrigailo began to reign in the Russian lands. His rebellion was crushed.
After the death of Sigismund, Casimir ascended the throne. During his reign, Lithuanian lands unite, the basis of the Uniate policy is restored. However, they remain highly unstable.
Casimir continued his successors - Sigismund and Alexander. After them, Sigismund-August took control. In the context of the ongoing struggle between the Russian state and Lithuania in 1569, the Union of Lublin was concluded in Poland. It was very important in the historical development of Central and Eastern Europe. After the conclusion of the union, the Commonwealth appeared - a new power, in which the Grand Duchy was able to maintain a certain independence.