Mombi herself enslaved King Pastoria, the last King to rule Oz, prior to the Wizard of Oz's arrival. She lived on a farmland which included corn fields, a four-horned cow, and some pigs. After arriving in Oz, the Wizard of Oz made three visits to Mombi, and handed King Pastoria's baby daughter, Princess Ozma, over to the old witch. Mombi kept the infant heir to the throne sucessfully hidden away, transforming her into a boy named Tip. Having been the jailor of Ozma's father and grandfather before, Mombi treated Tip as a slave too, as "he" grew up.