 Two of the "ie", founded by merchants in the early 17th century, survive today as Mitsui and Sumitomo, both major modern Japanese corporations.In the late 18th and 19th centuries, as Japan's economy continued to develop and modernize in many ways, the "ie" adapted, changing and growing to meet the demands of the new economic situation.Many became banks, trading originally in rice (which was essentially currency; see "koku") and later in paper and metal currency.