In Western Europe, after the fall of the Western Roman Empire, coins, silver jewelry and hacksilver (silver objects hacked into pieces) were for centuries the only form of money, until Venetian merchants started using silver bars for large transactions in the early Middle Ages. In a separate development, Venetian merchants started using paper bills, instructing their banker to make payments. Similar marked silver bars were in use in lands where the Venetian merchants had established representative offices. The Byzantine Empire and several states in the Balkan area and Kievan Rus also used marked silver bars for large payments. As the world economy developed and silver supplies increased, in particular after the colonization of South America, coins became larger and a standard coin for international payment developed from the 15th century: the Spanish and Spanish colonial coin of 8 reales. Its counterpart in gold was the Venetian ducat.