What is the background Shakespeare used to write this drama?

The Merchant of Venice was first printed in 1600 in quarto, of which nineteen copies survive. This was followed by a 1619 printing, and later an inclusion in the First Folio in 1623. The play was written shortly after Christopher Marlowe's immensely popular Jew of Malta (1589), a play wherein a Jew named Barabas plays a greatly exaggerated villain. The portrayal of Shakespeare's Jew was and remained comic until the late 1700s at which time he was first played as a true villain. In 1814 Shylock's role was depicted as a character to be pitied, and in 1879 he was first portrayed as a tragic character. Subsequent interpretations have varied greatly over the years, but since World War II he has most often been conceived of as tragic. Check this out: