https://historyofexploration.net/episode-10-strabo-and-the-roman-world/ https://historyofexploration.net/episode-11-the-silk-road-and-ancient-trade-routes/ https://historyofexploration.net/episode-12-pliny-the-elder-and-natural-history/ https://historyofexploration.net/episode-13-periplus-of-the-erythraean-sea/ https://historyofexploration.net/episode-14-ptolemy-and-the-world-map/