The trans-Saharan trade fell out of favor after the fall of Rome, because how hostile the terrain was (it was desert), and there were no "large 'country/empire'" to protect the traders from looters and other people who attack caravans for money, equipment, and other things. Rome offered protection to some of the caravans as they moved across the empire and the empire's allies land. However, after the fall, there were less organized military forces that traveled in more-'friendly' territory's and were less protected from burgulars. This led to a decline in the trade
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