if you had seen the entire episode, you would have had the answer to your question.. Zeugma was the site of one of the earliest bridges across the euphraties.. which is why it was a rich city.. traders and caravans passed throught the city to use the bridge.
(i thought they should have been looking for history/archiology of the bridge.. yes, the mosiacs were beautiful, but they have been found everywhere there were rich romans and greeks.. but ancient bridges.... now that would have been interesing!)

no doubt there were sites where you could ford the river (and thinking about it, ford/fjord seem definately germatic words.. what is the latin term for a ford (a place where one is able to cross a river with oxen, horses, etc?)
and there were ferries, but a bridge is a secure way to cross a river. (NY just had a ferry accident, i suspect in times past, they were more frequent, and costlier)

(we have lots of post on bridges/remember, a title for the pope is pontiff, (bridgebuilder) partly that is symbolic (a connection between christ in heaven and church here on earth) and partly its because bridge builders, were so important and esteemed in ancient times, that it was a title of extreemly high reguard.)



my other obsession