The Crusades brought a shift in European trade routes that accelerated the decline of Kievan Rus'. In 1204 the forces of the Fourth Crusade sacked Constantinople, making the Dnieper trade route marginal. At the same time the Teutonic Knights (of the Northern Crusades) were conquering the Baltic region and threatening the Lands of Novgorod. Concurrently with it the Ruthenian Federation of Kievan Rus' started to disintegrate into smaller principalities as the Rurik dynasty grew. The local Orthodox Christianity of Kievan Rus', while struggling to establish itself in the predominantly pagan state and losing its main base in Constantinople was on the brink of extinction. Some of the main regional centres that developed later were Novgorod, Chernigov, Galich, Kiev, Ryazan, Vladimir-upon-Klyazma, Vladimir of Volyn and Polotsk.
What helped restore the Kievam Rus?