Complex sentence: In 1419, the Grimaldis purchased Monaco from the crown of Aragon and became the official and undisputed rulers of "the Rock of Monaco", and in 1612 Honore II began to style himself "Prince" of Monaco.
Split into simpler sentences: In 1419, the Grimaldis purchased Monaco from the crown of Aragon and became the official and undisputed rulers of "the Rock of Monaco". In 1612 Honore II began to style himself "Prince" of Monaco.