Principality of Beloozero or Beloozero Duchy (Белозерское княжество in Russian

Russian language

Russian is a Slavic language used primarily in Russia, Belarus, Uzbekistan, Kazakhstan, Tajikistan and Kyrgyzstan. It is an unofficial but widely spoken language in Ukraine, Moldova, Latvia, Turkmenistan and Estonia and, to a lesser extent, the other countries that were once constituent republics...

) was a Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n principality or duchy

Duchy

A duchy is a territory, fief, or domain ruled by a duke or duchess.Some duchies were sovereign in areas that would become unified realms only during the Modern era . In contrast, others were subordinate districts of those kingdoms that unified either partially or completely during the Medieval era...

. It was formed in 1238 after its detachment from the Principality of Rostov

Rostov

Rostov is a town in Yaroslavl Oblast, Russia, one of the oldest in the country and a tourist center of the Golden Ring. It is located on the shores of Lake Nero, northeast of Moscow. Population:...

. The town of Beloozero (today's Belozersk

Belozersk

Belozersk , known as Beloozero until 1777 , is a town and the administrative center of Belozersky District of Vologda Oblast, Russia, situated on the southern bank of Lake Beloye, from which it takes the name...

) became its capital. Gleb Vasilkovich was the first prince

Prince

Prince is a general term for a ruler, monarch or member of a monarch's or former monarch's family, and is a hereditary title in the nobility of some European states. The feminine equivalent is a princess...

 of Beloozero (ca. 1238-1278). During his reign, the duchy's territory embraced the basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 of the White Lake

Lake Beloye, Vologda Oblast

Lake Beloye , is a lake in the northwestern part of Vologda Oblast in Russia. The lake has an approximately round shape with a diameter of . Its area is , and the are of its basin is and the area of its basin is . Lake Vozhe drains into the Sheksna River, which is a tributary of the Rybinsk...

 (Белое озеро, or Beloye ozero), lower streams of the Sheksna River

Sheksna River

The Sheksna is a river in Belozersky, Kirillovsky, Sheksninsky, and Cherepovetsky Districts of Vologda Oblast in Russia. It is a left tributary of the Volga River. It is long, and the area of its basin...

, and Lake Kubenskoye

Lake Kubenskoye

Kubenskoe Lake is a large and shallow lake in Vologda Oblast of Russia, situated at the height of 109 metres above mean sea level, stretching for 60 km from north-west to south-east....

.

In the 1st half of the 14th century, the duchy lost its significance. In 1389, it became an appanage

Appanage

An apanage or appanage or is the grant of an estate, titles, offices, or other things of value to the younger male children of a sovereign, who would otherwise have no inheritance under the system of primogeniture...

 of the Muscovy. In 1486, it was turned into Muscovy's uyezd

Uyezd

Uyezd or uezd was an administrative subdivision of Rus', Muscovy, Russian Empire, and the early Russian SFSR which was in use from the 13th century. Uyezds for most of the history in Russia were a secondary-level of administrative division...

. Numerous descendants of the ruling Rurikid

Rurik Dynasty

The Rurik dynasty or Rurikids was a dynasty founded by the Varangian prince Rurik, who established himself in Novgorod around the year 862 AD...

princes moved to Moscow and continue in a male line to the present.