How we know about him change
In the Gallus Anonymous Chronicle we can read about him as a Duke of Polans before Mieszko I. He is also mentioned in many other chronicles.
What we know about him change
We don't know a lot about him. Perhaps he caused the wkrzanie uprising in germany. He centralized the country a lot, beacause before baptism of Poland, this country was quite centralized as a Pagan country. He probably also conquered Goplans and Mazovians.