Like Alexandra said, Andrew (or Andreas) II, King of Hungary, is a historical person, early 13th century, one of the leaders (Alexandra, I wouldn't exactly use the word "heroes" in the context of the Crusades, though

) of the Vth Crusade. His brother-in-arms Jean de Brienne seems also to have been a real person.
The story of Raymonda is located in the Provence, in southern France, which provides a link with the troubadour figures Bernard and Béranger, the two friends of Raymonda. The last Act takes place in the Provence as well, but is an homage to the Hungarian guest, King Andrew (whom in reality was beaten during the Crusades and made a far less glorious return home).
Interesting to know that Petipa initially wanted to locate the 2nd Act in Cordoba or Granada, in the Arabian conquered part of Spain, where he could place all the oriental dances.