Beginning in the 1160s, the opening of new silver mines in northern Europe led to the minting and circulation of vast quantities of silver coins.The widespread use of cash greatly increased the volume of international trade.Business procedures changed radically.The individual traveling merchant who alone handled virtually all aspects of exchange evolved into an operation involving three separate types of merchants: the sedentary merchant who ran the "home office” financing and organizing the firm’s entire export-import trade; the carriers who transported goods by land and sea; and the company agents resident in cities abroad who, on the advice of the home office, looked after sales and procurements. (来源:托福考试TPO 46的阅读理解)
简单来讲,北欧银矿发现之前,大家几乎都是旅行商人。
顺带一提,这个动画里和经济学有关的细节都是真实的。无论是香料贸易(黄金和胡椒等价,动画里天秤的左边是胡椒,右边是黄金),或是期货交易(利用黄铁矿泡沫击败阿玛)都不是乱讲的。