Simplify the following text for a Grade 8 native English-speaking person.
Original: The artificial island was constructed in 1634 on orders of shogun Iemitsu , originally to constrain Portuguese merchants living in Nagasaki .
Simplified: Shogun Iemitsu ordered the creation of the artificial island in 1634 . He did this at first to keep the Portuguese merchants living in Nagasaki in one area .