Along with battles, geographical discoveries and other significant achievements, repeatedly described by historians, local historians and publicists, our history also remembers other events. Not as well-known due to certain circumstances, but no less important for the process of formation of Ukrainian statehood than those that we read about on the pages of school textbooks. Perhaps the most striking example of such a historical event that has been unfairly neglected by scientists is the Battle of the Sinyukha River. Or, as it is also called, the Battle of Blue Waters, which took place in the fall of 1362 in the area of the modern village of Torgovitsa in the Kirovograd region. It is easy to underestimate the significance of the victory that the Lithuanian prince Olgerd Gediminovich won on the banks of Sinyukha over the troops of the Tatar princes Kochubey, Kutlu-Buga and Dmitry impossible, and below we will try to explain in detail why. And at the same time, answer the question: why exactly the Battle of Kulikovo, which took place 18 years later in 1380, is considered the starting point that ended Tatar-Mongol rule in the lands of Kievan Rus?