It marked the ancient border with Nubia to the south and was the conduit for the camel caravan trade in African products such as gold, ivory, and spices.
The border is 60 miles long.
mnli hypothesis: The border is 60 miles long. premise: It marked the ancient border with Nubia to the south and was the conduit for the camel caravan trade in African products such as gold, ivory, and spices.