Ronia the Robber's Daughter (Swedish: Ronja Rövardotter) is a children's fantasy book by the noted Swedish author Astrid Lindgren, first published in 1981.
Set in the early Middle Ages, Ronia, the main character, is a girl growing up in a clan of robbers, who lives in a castle in the woodlands of Scandinavia. As the only child of Mattis, the chief, she is expected to become the leader of the clan someday. Their castle, Mattis's Fort, is split in two parts by a lightning bolt on the day of Ronia's birth. Soon afterwards, a different clan of robbers, the "Borkas", settles the other side of the mountain, resulting in much strife between the two clans. Ronia grows up with Mattis's clan of robbers as her only company. One day, Ronia sees Birk Borkason, the only son of the enemy chieftain, Borka, idling by the chasm that splits the two parts of the castle. He is the only other child she has ever met, and so she is sorry that he is a Borka. He engages her in a game of jumping across, which does not end until Birk almost falls down. Ronia saves him and they become friends.
The following winter is long and cold and although Mattis's robbers are well fed, their counterparts are suffering on the other side of the chasm. Ronia brings food to Birk through a secret passageway. They get very close but both know that they cannot tell their families. Later that year Birk saves Ronia from being captured by the faeries only to be captured himself by Ronia's father. Ronia gives herself to the Borkas so she must be exchanged, but as a result her father disowns her and refuses to acknowledge her as his daughter. Birk and Ronia run away to the woods. Ultimately their families repent of their feuding, and everyone is reunited.