In Rogozhsky chronicler in article 6871 (1363) we read:
That same autumn Algirdas Blue Water and Beloberezhe some fighting.
To better understand where did this message and what it means, we will look at all posts Rogozhsky chronicler of the 1355 – 1374 years.
1. Entries Rogozhsky chronicler of the 1355 – 1374 years, are based on two sources – the proto-Tver and proto-Moscow chronicles. Approximate time of their occurrence – 1375 – 1380 years, that is, they are contemporaty and prestigious themselves.
2. The geographical horizons Rogozhsky chronicler limited to the lands of the Great Russia and even closer – to the Tver and Moscow principalities. He did not knew any geographical names (and, consequently, events) on the territory of modern Belarus and Ukraine.
3. The message of the attack on Blue Water should be considered in the context of the numerous attacks Lithuania on the Tver principality, mostly in its south-western frontier. These attacks are relatively often fixed in detail in Rogozhsky chroniclers.
4. Name Blue Water refers to a modern small river Sinya (Blue), which flows into the river Dyorzha near town Pogoreloe Gorodische. Dyorzha River 2 km from the confluence of the Volga River cuts through the mountains of white limestone that with some caution may be considered as Beloberezhe.
5. In the documents of the 16th century Blue River basin formed Blue parish, which belonged to Staritsky principality.
6. Record Nikon Chronicle of Blue Water borrowed together with a large series of other records from Rogozhsky chronicler. Nikon Chronicle does not provide any new information about the event, and should be considered as a secondary source, depending on the Rogozhsky chronicler.