What tribes are the Slavic peoples divided into?

At the beginning of the Middle Ages, Slavic peoples settled across the European plain. They began to occupy vast territories. Then three branches of the Slavs were formed: eastern, western and southern. These branches were divided into tribes and tribal alliances. The eastern territories were inhabited by glades, Drevlyans, Radimichi, Polochans, Krivichi, Ilmen Slovenes, Vyatichi, Volynians and others. They differed in level of development and culture, but they were united by common interests and trade. Most of the tribes were on the banks of rivers and lakes.