Simplify the following text for a Grade 7 native English-speaking person.
Original: When the latter was sold to the Visconti of Milan in 1398 , the island was acquired by the Appiani , Lords of Piombino , who retained it for two centuries .
Simplified: In 1398 , was sold to the Visconti family of Milan . After a few years , the island was acquired by the Appiani , Lords of Piombino , who kept it for two centuries .