the sumitomo group, of which sumitomo corporation is a key member, dates to the 17th century establishment of a book and medicine shop in kyoto by masatomo sumitomo. sumitomo's brother-in-law riemon soga developed a technology to extract silver from copper, and soga's son (who married sumitomo's daughter) tomomochi sumitomo expanded this smelting business to osaka. from this start, the sumitomo family expanded its business into copper mining (the besshi copper mine), followed by textiles, sugar and medicine trading.