Hoi An, founded 2000 years ago, became the port cum commercial capital of the Champa Kingdom during 7th-10th c., and was an important international port in 16th-17th c. before the role was usurped by Da Nang during the French rule. It has been influenced by the Chams, Chinese, Japanese, Dutch, Arabs and French. The Arab traders converted some of the Chams to Muslims, and they migrated to Cambodia, and some even say to the Pattani/Kelantan area of the Malay Peninsula.
My Son is the site of ruins of Hindu temples from the Champa Kingdom (3rd-18th c.). Structures dating from the 7th c. are being preserved and gradually restored.