1. Fairs of Champagne. In the 11th and 12th centuries, these developed as major centers of long-distance trade and exchange. As cities concentrate trade in space, the fairs concentrated a more limited volume of trade in time, different fairs operating at different times of the year, maximizing the prospect that merchants would find customers offering goods in exchange. Fairs were also points at which Italian financial innovations spread into Northern Europe. The fairs declined as cities developed, and with the emergence of the sea route from the Mediterranean to northern Europe.
2. Three-field system of agriculture. This was the basis of medieval crop rotation, with fields alternating between crops that severely depleted soil nutrients, crops that produced less stress, and lying fallow for replenishment. The overall effect of the three-field system was to allow higher productivity û allowing a 50 percent increase of farmland under cultivation, from half to two-thirds û thus supporting a larger population, without exhausting the soil. The three-field system also used labor and capital (e.g., plow teams) more efficiently through the year. The three-field system became widespread in the north, but never so widely used in Italy.
3. Serfdom. This was a legal status in which peasants were bound to the soil, and required to provide labor service or in-kind dues to the lord of the land. Though a form of bondage, it differed from slavery in that the serf could not be arbitrarily turned off the land, a matter of great importance to peasants. From the lord's point of view, serfs might be less convenient than slaves in that his control over them was not total, but serf populations tended to be self-replacing, as slaves often were not. From the serfs' own point of view, though not free, they had a right to their land, and could consume or exchange production beyond that obligated to their lord. In Western Europe, serfdom gra...