Remember Aragorn's assertion that boats used to travel south out of Wilderland down to Osgiliath, until only a few years before the War of the Ring. They must have been used for trade between Gondor and at least the men of the Anduin vale above the Gladden Fields - the Woodmen and the Beornings.
And it's certain that this North/South trade would cross over the Lindon - Bree - Beornings - Woodland Realm - Erebor - Esgaroth - Iron Hills - Dorwinion trade route.
|