In certain ways, The Merchant of Venice by William Shakespeare is a realistic description of Venice, one of the great mercantile cities of the late middle ages and Renaissance. Although many aspects of the plot are obviously fictional, the description of the great merchant fleets and their roles in the Venetian economy actually reflects how people lived.
The first element that is realistic is the role of Jewish moneylenders. Because the Roman Catholic Church in that period defined lending money for interest as usury and forbade it, Jews, who were otherwise somewhat of an isolated and persecuted minority, were allowed to engage in moneylending, albeit in a heavily regulated manner. Because the Jewish community was both tightly knit and oppressed by Christians, Shylock's hatred of Christians and unwillingness to let his daughter marry one is also historically probable.
The other way in which Shakespeare reflects the actual life of Venetian merchants is in his portrait of the uncertainty of mercantile life. The merchant was very much of an entrepreneur, investing in risky ventures. Trading ships could be the source of winning or losing great fortunes, and Antonio's fiscal difficulties,l include lack of what we now would call liquidity, and financing by a Jewish moneylender, all reflect actual conditions of the period.