Simplify the following text for a Grade 9 native English-speaking person.
Original: Jien records that Suizei was one of the sons of Emperor Jimmu , and that he ruled from the palace of Takaoka-no-miya at Katsuragi in what will come to be known as Yamato province .
Simplified: The GukanshÅ records that Suizei ruled from the palace of Takaoka-no-miya at Katsuragi in what will come to be known as Yamato province .