Another explanation I’ve heard is that the sea routes were working more effectively and this impoverished the caravaneers.
Mo worked the camel caravans. When pirates or predatory governments made movement of goods via the Red Sea or Persian Gulf too expensive, merchants switched to camel caravans across the Arabian Peninsula, which were of course much more expensive than water shipment otherwise. This was the major economic activity of Arabia, supporting most of the townspeople like Mohammed’s clan. Even the Bedouin depended on the caravans. No caravans, raiding isn’t very profitable.
Supposedly an economic crisis in the peninsula preceded the Muslim explosion, possibly caused by switch to water rather than land shipment.
add the comments by wideawake (from 2004):
The Nabataeans were an Arabic people who lived on the eastern borders of the Jews. They spoke Aramaic and they were allies of the Romans. Their religion was apparently a mixture of Arab paganism with tinges of Judaism and Christian influences as well.
If the Koran shows as heavy an Aramaic influence as this guy suggests, it makes it pretty likely that the Koran is just cobbled-together fragments of eclectic Nabataean religious texts.
Just as many Jewish texts are written in a blend of Aramaic and Hebrew using Aramaic script, the Koran could be a blend of Arabic and Aramaic in Arabic script.
This would explain the thousands of words and phrases in the Koran that are obscure and that have provoked endless commentary. It would also explain why the Koran is so disorganized and shuffled. It is the least coherent, in terms of narrative structure, of any major Near Eastern text.
and we have a pretty good idea of the beginning of the problem.