Africa produced a lot of the raw materials, like animal hides and skin and ivory and gold. The Swahili city-states imported finished goods, such as silk and porcelain from China and cotton cloth from India. Spices and foodstuffs, like rice, were shipped from Southeast Asia, and especially Sri Lanka, where black pepper was a primary export. And the Islamic world provided everything from coffee to books to weapons. But it wasn't just products that made their way around the eastern hemisphere thanks to the Indian Ocean. Technology spread, too. Like the magnetic compass, which is kind of crucial if you like to know where you're going, came from China.