Complex sentence: Novgorod was a centre of paganism in the Dark Ages, and the Peryn isle has its name due to the Slavic god Peroun whose shrine was located there in the 9th century.
Split into simpler sentences: Novgorod was a centre of paganism in the Dark Ages. The Peryn isle has its name due to the Slavic god Peroun whose shrine was located there in the 9th century.