Mulan is discluded because she was not born, nor did she marry into, royalty. I hesitated on Pocahontas until I remembered that Disney decided she was an "Indian Princess". Even though there is not and never has been such a thing as a Native Monarchy and therefore the concept of an "Indian Princess" is absurd. But I guess it made for a quickly relatable way for kids to understand that Pocahontas was in a privileged position of power and that her getting married was a big deal. But still. You'd think "Chief's Daughter" would have sufficed.