Simplify the following text for a Grade 8 native English-speaking person.
Original: He is traditionally believed to have ruled from the palace of Migario-no-miya at Karu in what will come to be known as Yamato province .
Simplified: The GukanshÅ records that he ruled from the palace of Migario-no-miya at Karu in what will come to be known as Yamato province .