Trade continued, to the extent that Chinese silks have been found in Bavarian tribal members’ graves dating to the 6th century. Gemstones from India and Afghanistan found their way up the Rhine and Rhone, while amber, furs, and slaves went south and east. Now, the trade did not reach the scale of the Empire at its peak. Even if population shifts had not affected the “European” economy, the weather shifts in the late 400s and after 526 made life much harder on everyone. No more wine from Britain or up around Mainz, no more wheat exported from the Low Countries to Rome. But archaeologists find trade. And they find continuity.
So, more the cold ages than the dark ones…..