Aye, roasting occasional goblin trespasser
This dusty topic proved to be very interesting, so I want to revive it a bit for the newcomers.
Per instance, what of the trade was with the west partners, whatever befell? The men of Anduin's vale were not thatcivilized after all, to have advanced agriculture. Dwarves had no difficulty to bring up goods for Bilbo's party from Erebor, so the distance of trade may be counted as a weak argument against West trade theorem. Also, there is 'great passage of dwarves' through the Shire mentioned somewhere. In the west there were dwarven mines in Blue Mountains, but what was the need of such a comings and goings to the East? It seems too me it was not so difficult to establish trade not only with Western dwarvish settlements, but even with the Shire itself (why not, if even Saruman was able to get pipe-weed there?)
looking up Tale of Years:
1601 - Shire established
1636 - The great Plague, Eriador is desolate, but Shire survives
1981 - Moria is left by dwarves
Between 1636 and 1981 there were all possibilities to trade to the West
More speculations, of course, but to the barrier, gentlemen!