Finnish–Novgorodian wars

ELI5: A long time ago, the people who lived in Finland and Novgorod (which is now part of Russia) didn't get along very well. They had different ideas about who should have power and control over the land. So, they fought a lot of wars against each other. The Finland people were called "Tavastians" and they had very good fighters called "warriors". The Novgorod people were called "Russians" and they had lots of soldiers too. The wars went on for many years, but eventually the Novgorod people won and they got to control the land.