Medieval Europe was economically cruder than the Roman Empire it replaced

Evidence

Still, we must not forget that in historical reconstruction, a medieval age is to be intervened between these two ages. Medieval Europe, though still agricultural in economy, was a much cruder existence for slave, peasant, farmer, artisan, land-owner, cleric, and nobility alike than had been the circumstance for their predecessors in the Empire. Urban life declined, leaving the old cities in ruins, long-distance trade, especially by sea routes, decayed dramatically. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 132