Aden was Yemen's main port in the 16th century. It was largely a transhipment port. The famous gum arabic was produced in the dry hinterland. Aden also produced incense. During the 17th century the town was eclipsed by the rise of Mocca, a centre for the coffee trade. The town walls remained intact but Aden's beautiful town centre became run down. Between 1614 and 1620 the VOC briefly operated a trading office in Aden. The aim was to sell spices in Yemen, so generating the cash required to by goods in the north-west Indian town of Surat. But trade was hindered by the struggle of the Arabic Yemenites against their Turkish rulers. The VOC had little success selling its products. Nevertheless, the Company continued sending ships to Aden after 1620.