This study examines the long-term reversal effect in commodity spot markets using seven centuries of data. The research is the longest study of the long-term reversal effect covering 52 agricultural, industrial and energy markets from 1265 to 2017 employing U.K.- and U.S.-based commodity prices. Returns over the previous one-to-three years negatively predict subsequent performance in the cross-section of returns. The long-run reversal effect is strong and robust after surviving a variety of robustness checks. The effect cannot be explained by statistical biases, extreme events, or macroeconomic risks. The study reveals that the long-run reversal effect is driven by supply-and-demand adjustments in physical commodities through time.