When did coastal trading cities begin to arise along the East African coast?

Coastal trading settlements began to emerge along the East African coast as early as the 8th or 9th century. While earlier accounts from the 1st century CE mention trade in the region, such as at the town of Rhapta, no physical settlements from that period have been discovered.12

A new era of development opened in the 9th century, marked by the appearance of the first identifiable building sites. Notable examples include:1

• Manda: Established in the 9th century near Lamu, this site featured coral block seawalls and engaged in significant trade with the Persian Gulf.1
• Kilwa: Ruins at this location likely date to the 8th or 9th century, showing a progression from pre-Muslim settlement to the construction of coral masonry walls by the 10th century.1

These early coastal towns were primarily situated on islands for security and served as hubs for exporting goods like ivory, tortoiseshell, and ambergris. By the 11th century, these settlements were increasingly influenced by Islam, and by 1300, many had evolved into established Muslim towns.1