Simplify the following text for a Grade 6 native English-speaking person.
Original: Princess of Orange were women married to the Sovereign Princes of Orange during their reigns from 1171 to 1815 , and the heirs to the Dutch throne , who were titled Prince of Orange , since 1815 .
Simplified: Princess of Orange is the title ( name ) used for the women who were married to the Ruling Princes of Orange in the time between 1171 to 1815 . Since 1815 , it was also used for the wives of the heirs to the Dutch throne , who were titled Prince of Orange .