Medieval trade links were well-established and prosperous, facilitating the movement of goods between Africa, Europe and the East, and the spread of Islam. In North Africa, Muslim traders sent luxury goods such as textiles, beads and ceramics south, while gold, African ivory, kola nuts and slaves moved north. Huge caravans of over 1,000 camels crossed the Sahara; Saharan nomads acted as guides and sold meat and salt. Gold was sought after for coins, art, jewellery and ornamentation, and this precious commodity moved both north and east. Along the east coast, the Indian Ocean trade routes created a string of prosperous cities and trade between Africa and Asia flourished. Ivory, gold, ebony, sandalwood and slaves were traded for Asian cotton, silk and porcelain. City ports became wealthy centres of trade, attracting merchants from the Arabian Peninsula, India and Southeast Asia. Soon, inter-racial marriages gave rise to a new ethnic group – Swahili – and the Swahili states became major economic powers.