Champagne fairs took place in the Middle Ages in the County of Champagne, east of modern France. Their location between Flanders and Italy placed Troyes and its region at the heart of trade routes. The fairs took place twice a year and lasted three to six weeks. They marked the beginnings of the organization of the modern market economy. A unit of weight, the marc de Troyes, appeared in 1147 and was adopted in Paris. The denier provinois was the currency of the fairs and was in use as far as Italy. The Troy ounce is still the international mass reference for precious metals today.