the sumitomo family was close to the tokugawa shogunate throughout the edo period. during the 1860s, this relationship became a liability for the firm as the tokugawa clan warred with rivals in western japan. following the tokugawas' defeat, sumitomo was almost ruined and under pressure to sell the besshi mine, which by that point was nearly unworkable. however, sumitomo kept the mine and improved its output through adoption of new western techniques. during the rapid westernization of japan in ensuing decades, sumitomo started various new trading, manufacturing and financing businesses, becoming one of the major "zaibatsu" of early 20th century japan.