Principality of Chernigov
In the southern portion of the Kievan Rus' the city was the second by importance and wealth. From the early 11th century it was the seat of the powerful Grand Principality of Chernigov, whose rulers at times vied for power with Kyivan Grand Princes, and often overthrew them and took the primary seat in Kyiv for themselves. The grand principality was the largest in Kievan Rus and included not only the Severian towns but even such remote regions as Murom, Ryazan and Tmutarakan. The golden age of Chernihiv, when the city population peaked at 25,000, lasted until 1239 when the city was sacked by the hordes of Batu Khan, which started a long period of relative obscurity.