Kievan Rus%27:

Due to the expansion of trade and its geographical proximity, Kiev became the most important trade centre and chief among the communes; therefore the leader of Kiev gained political "control" over the surrounding areas. This princedom emerged from a coalition of traditional patriarchic family communes banded together in an effort to increase the applicable workforce and expand the productivity of the land. This union developed the first major cities in the Rus' and was the first notable form of self-government. As these communes became larger, the emphasis was taken off the family holdings and placed on the territory that surrounded. This shift in ideology became known as the verv'.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". How did the leader of Kiev gain political control?
Due to the expansion of trade