Exploring the Swahili Coast: The Legacy of Shirazi, Wadiba, and Hilaalee Rulers and Their Influence on the Cowrie Shell Trade. The maritime expanse of the Western Indian Ocean,historically referred to by Arab cartographers and merchants as the Bahr al-Zanj, was never a barrier dividing civilizations, but a fluid highway connecting East Africa, the Comoros archipelago, and South Asia. Far from isolated, pre-modern societies, the coastal emporiums of the Swahili Coast and the c