Okay kiddo, so a long time ago there was a big fight between two groups of people over who would get to live on a certain piece of land. This fight happened by a river called the Belly River, because it kind of looked like a big belly.
One group of people was called the Blackfeet, and they were really good at fighting and hunting. The other group was called the Cree, and they were also pretty good at those things too.
The Blackfeet and Cree had been fighting over this land for a while, but things really heated up one day when the Blackfeet attacked the Cree camp by the river. The Cree fought back hard, but the Blackfeet were just too strong.
In the end, a lot of people got hurt or even killed. It was a really sad and scary time for everyone involved.
But the good news is that eventually, the Blackfeet and Cree made peace and learned to live together on that land. It took a lot of time and work, but they realized that it was better to work together than to keep fighting each other.