Numerous princely feuds, large and small wars between different lords, were tearing Rus. However, the ancient Ukrainian state did not fall apart. It only changed the form of its government: The personal monarchy was replaced by the federal one, Rus came to be co-ruled by the group of the most influential and powerful princes. Historians call this way of governing "the collective suzerainty." The Principality of Kyiv remained a national center, and the residence of bishops.