traders, merchants, sailors and pilgrims, and led to the creation of port cities. The monsoon winds, blowing from the south-west from June to November and from the north-east from December to May, led to trade between Egypt (then a Roman colony) and India from the first century BCE onwards, thus 'provincializing' the Roman Empire (Fitzpatrick, 2011), and later between Africa and Asia. After 1250, a string of independent stone-built towns on the eastern African coast - Kilwa, Sofala, Mombasa, Malindi, Mogadishu - were linked to Surat, Calicut, Aceh, Mocha, Hormuz, Basra, Malacca and Guangdong. Gold, ivory, iron, frankincense and cinnamon were sold to Europe, India, South-East Asia, and China and cotton, silk, and porcelain objects arrived from Asia. By the 1400s, the Swahili city-States formed a major world economic power.