What factors led to the revival of trade in Western Europe between 1000-1200 ?
Within Europe, the warming climate during the Middle Ages made for ideal conditions to increase the yield of wheat, barley, and grapes for wine. This led to an Agrarian Revolution, in which not only were yields improved by better climatic conditions, but new agricultural techniques were developed, such as the three-field rotation, and the use of horses instead of oxen, the horses being more efficient beasts of burden and ploughing. All these agricultural changes led to an increase in the food supply, which created town centers as an area for the exchange of produce. As the population and standard of living increased, a division of labor and specialization occurred. This allowed for the beginnings of the guilds, where skilled craftsman could promote their goods and services, which also stimulated trade.
Externally, the Crusades, beginning in 1095, brought an emerging European power into the Middle East, nominally to free the Holy Land; more practically, Europe desired the reopening of trade routes and markets closed by the Muslims.