Hey there kiddo! So, do you know what a will is? It's a paper that people write to say what they want to happen to their things after they die. That's sort of what the Testament of Bolesław III Krzywousty is like.
Bolesław III Krzywousty was a king in Poland a long, long time ago. When he knew he was going to die, he wrote down some things he wanted to happen after he was gone. He wrote them down in a special document called a testament.
In his testament, Bolesław III Krzywousty said who should be the next king after him. He also wanted his land to be divided up between his sons. He even said what each son should get and said they should all be equal.
The testament was important because it made sure that Bolesław III Krzywousty's wishes were followed after he passed away. It helped keep things fair among his sons too.