Trade and traderoutes in M-E

[Inziladun]

During my re-reading of The Hobbit I found something that might bear on this subject.

There stood barrels, and barrels, and barrels; for the Wood-elves, and especially their king, were very fond of wine, though no vines grew in those parts. The wine, and other goods, were brought from far away, from their kinsfolk in the South, or from the vineyards of Men in distant lands.

The Hobbit Barrels Out of Bond (emphasis added)

Granted, it is The Hobbit, so a small pinch of salt might be in order.
But still, who could the 'kinsfolk in the South' possibly be? The Lórien Elves were to the Southwest, but Celeborn's words to Legolas,

Welcome son of Thranduil! Too seldom do my kindred journey hither from the North.

would seem to indicate there wasn't much contact between the two realms.
At any rate, the Forest River and the R. Celduin would not seem to be viable trade routes for any commerce between Thranduil's people and other Elves.