A i think is the correct answer
The trading route most likely happen by ships through the Mediterranean Sea.
The only option besde that would be by land. But the distance required to do by land is further than those the sea and it has to pass the territory of Greece and Turkey, which will guarantee additional toll payment and reduce the traders' profit.
The geological terrain of this region is primarily steppe, grasslands which have poor soil for agrarian (agricultural) lifestyles. Historically, steppe people have had to rob agricultural societies (i.e. Mongols in China) or just eat meat they hunt.
