Complex sentence: The only information about him is contained in the 12th-century Russian Primary Chronicle, according to which Rurik was a Varangian chieftain of the Rus who gained control of Ladoga in 862, and moved his capital to Novgorod in 864.
Split into simpler sentences: The only information about him is contained in the 12th-century Russian Primary Chronicle. Rurik gained control of Ladoga in 862, and moved his capital to Novgorod in 864.