These were known as the intense trade routes which are a major network of land and sea routes, linking the Mediterranean world with eastern and southern sources of species stretching from North Africa and Arabia.
A most important part of this route was the Persian Gulf due to its prominent position Yemen attracted people to settle in fertile crescents. The third-century seemed to be significant for the Arabian traders as the nature of trade completely changed.
Drastic climatic conditions disrupted the trade which was brought to a halt by the poor economic conditions. As a fall in the coffee production and decline of ports such as Alexandria led to the decline.