Кубенское озеро
The principality was detached from the Principality of Rostov in 1238. The town of Beloozero (today's Belozersk) became its capital. Prince Gleb was the first prince of Beloozero (ca. 1238–1278). He increased his standing enormously by marrying Sartaq's daughter. The later rulers of Beloozero could claim a descent from Genghis Khan through this marriage. During Gleb's reign, the duchy's territory embraced the basin of White Lake, the lower streams of the Sheksna River, and Lake Kubenskoye.