Trading on foot is a tough business – you can only exchange what you carry. See how improved transportation changed the trade landscape.
As trading between regions and countries became more important, so did travel. In fact, trade and travel link so completely that discussing one involves discussing the other.
Improvements in transportation made it easier for merchants to trade in distant markets. In early Bible times, trade between countries probably took the form of diplomatic exchanges between kings and had little impact on the economic life of the ordinary people. Most peoples created enough goods and services in their local economies to satisfy their daily needs. However, in later times, trade would increase as transportation improved, making possible the spread of ideas, culture, and material wealth. Unfortunately, this would also give rise to wars and the struggles to maintain empires.