Answer: The Abbasids built Baghdad from the onset. Baghdad later became the trade middle point between Asia and Europe. The Abbasids built a reliable road network for trade.
Step-by-step explanation:
The Abbasids built Baghdad from the onset. Baghdad later became the trade middle point between Asia and Europe. The Abbasids built a reliable road network for trade. They overthrew the Umayyad dynasty in 750 CE, and moved the capital to Baghdad. This made the Persian bureaucracy replace the Arabic method of governing
The most important factor was the small land border, this made the Muslim presence in Spain possible.