The sources available for the study of economic history in Venice are relatively limited compared to many other northern Italian city-states, and they certainly pale in comparison to the documentary riches of the Florentine archives. The archives of the state magistracies regulating commerce have suffered serious losses and the majority of the documentation dates to the sixteenth century and later. The historiography of medieval merchants and commercial culture in Venice has thus focused on close analysis of a few examples rather than on serial or statistical analysis. The territory that Venice conquered, colonized or ruled directly also had essential functions in the Venetian economic system. In the thirteenth century, Venetian power extended through the eastern Adriatic to the island of Crete and the Peloponnesian port cities of Coron and Modon. In the early fifteenth century, Venice began a programme of political and military expansion on both the mainland and in the maritime realms.