Simplify the following text for a Grade 7 native English-speaking person.
Original: Pope Sixtus IV ( July 21 , 1414 - August 12 , 1484 ) , originally Francesco Della Rovere , was pope from 1471 to 1484 .
Simplified: Pope Sixtus IV ( July 21 , 1414 -- August 12 , 1484 ) , born Francesco della Rovere , was Pope from 1471 to 1484 .