Ed,
I think that I may not have properly emphasized, it was not that any sort of profit oriented trade or materials were being 'brokered' via these trade routes and networks, it is simply that these networks were a conduit for 'influences'.
If I travel to Europe, and am wearing a pair of boots from Texas, is it possible that someone or even a number of people might find them interesting, and wish to also have this kind of boots. While my purpose there might have nothing to do with selling boots, still they have attracted interest, and perhaps initiate some degree of influence.
It was not about transiting goods into these other regions, but the fact that caravans did traverse through many regions and connect with other caravans from other regions. Is it not possible that just normal human interaction, not commerce, might have exposed and transmitted influences across these great distances?
We see this constantly in fads, fashions and popular culture. The interest in something 'exotic', unusual to ones locale, and which would be thought to enhance ones status or mystique.
The Swahili factors in the Great Lakes who were operating along with Omani merchants of course had no interest in Darfur or the Manding, if they had even ever heard of them. However, 'things' which came from those regions were certainly of interest in some degree, even if only a curiosity.
Burton (and Demmin, 1877) both saw the so called Zanzibar swords (with an H type hilt), but had no idea these intriguing dirk like swords had originated in Morocco, also on the other side of the continent.....and were actually the local daggers termed s'boula.
How had they arrived in Zanzibar? Was it Moroccan agents setting up shop in Zanzibar? Of course not, but somehow, these had arrived in Zanzibar and in sufficient number to have been thought from there by these observers. It was not until Buttin (1933) set the record straight.
The diffusion of such things as styles, ideas, fashion, religion and others does not require a structured system of transmission, nor profit oriented agency in certain contact points to move in fact. almost randomly. This is primarily what I was trying to say.
