In the 13th century. The principalities of Ancient Rus' and the states of Eastern and Central Europe experienced the stunning onslaught of the military machine of the Mongol Empire, literally sweeping away everything in its path. The campaign of 1236–1242 was grand in scale. (the total forces of the Mongols amounted to an astronomical 250–260 thousand people) went down in the history of wars as the Great Western Campaign. The population of the conquered areas hoped to sit outside the walls of the cities, but the Mongols not only had a rich arsenal of technical means for taking fortifications - they had experienced engineering and stone-throwing artillery units. The extreme western point of Batu Khan’s campaign in Europe was Poland, the Czech Republic and the Kingdom of Hungary (it included Hungary, Slovakia, and a significant part of the former Yugoslavia), and in 1242 the Mongol army reached the “last sea” - the Adriatic. In 1243, Batu received the first Russian princes in the capital of the Golden Horde, who arrived with an expression of submission. On the pages of this book, a famous specialist in the military history of the Mongol Empire gives a broad picture of the forces and capabilities with which the conquerors established political dominance over the Russian principalities, which lasted from the middle XIII to XV centuries, and a large part of Eastern Europe. For the first time in historical literature, solely on the basis of sources of the Mongol Empire (internal documents of the Mongol state, its interstate acts, official and unofficial reports, eyewitnesses who visited Mongolia and Mongol headquarters), the organization, weapons, tactics and combat use of the army of the empire of Genghis Khan and his first successors.