The most important urban centers of Arabia were Makkah and Yathrib...

The most important urban centers of Arabia were Makkah and Yathrib, both in Hijaz. The citizens of Makkah were mostly merchants, traders and money-lenders. Their caravans traveled in summer to Syria and in winter to Yemen. They also traveled to Bahrain in the east and to Iraq in the northeast. The caravan trade was basic to the economy of Makkah, and its organization called for considerable skill, experience and ability. R. V. C.