What are the reasons for the appearance of local reigns among the Eastern Slavs?

At the turn of the 8th and 9th centuries, principalities began to emerge on the Slavic lands, which later represented a state – Kievan Rus. The reason for this was that with the help of centralized power it was possible to create an administrative system and a tax system that could solve most of the global problems and tasks. This also includes the issue of protection from an external enemy. When a principality arose, with its center in one city, finances and other resources flocked there. As a result, it was possible to keep a squad that would defend the territory of the principality from enemies. Also, now the entire land of the principality and its population was represented by the prince, who defended the rights of his people.