Early trading networks carried relatively small quantities of valuable goods, often over considerable distances, both by land and water. The relationship between overland transport and carriage by river or sea helps to explain why trading centres rose to prominence at certain key positions on these routes. With very small quantities of goods, light vessels might be carried over short distances between rivers; and even when the bulk of traded goods increased, it might still be advantageous to carry the goods for short distances overland from one port to another. Sites at such break-of-bulk points became major nodes in the transport network. This presentation explores the changing geometry of early trade-routes, and especially the interface between land and sea.