[piosenniel]

I would think that since many of the trading based clans moved about quite a bit (and I'm sure probably went as far north as the main bazaar in Umbar) that common trading dialect and Westron might have intermingled. And that the members of a particular clan who did the most trading or represented the others of the clan in their trading might know enough Westron to get by.

My dad was raised in the Phillipines. There were numerous, discrete dialects spoken on the various islands. Pidgin, a trading dialect cobbled from the various main languages including those of the traders who were English and Spanish speakers, was used as the lingua franca. Forms of Pidgin were also used along the trading routes among the islands chains in Micronesia, Melanesia, and Polynesia, so that everybody could get their business done.