For 500 years after the fall of the Western Roman Empire in 476 A.D., a period known as the early Middle Ages, Europe endured an age of political instability, economic decline, and reduced population. But as the millennium approached, the situation began to improve. Toward the end of the tenth century, an increase in the amount of crop-producing land was accompanied by an increase in population, with the potential for that number to rise even higher. The increase in agricultural production came about as a result of a combination of factors, the most prominent of which were changing methods of field management and improvements in agricultural technology. For much of the early Middle Ages, peasants continued the Roman practice of dividing their fields in two leaving one fallow, or uncultivated, for a year, and planting their crops in the other half. Fallow land restored its nutrients, but the practice meant that half the land produced nothing every year. In southern Europe – with its drier climate – this system of two-field crop rotation continued, but in northern Europe, peasants improved on this system by dividing their land into three parts. One they left fallow, another they planted in the spring, and the third they planted with winter crops. This three-field crop rotation, dependent on more rainfall than southern Europe received, meant that two-thirds instead of one-half of a peasant's land was under production in one year. Related to the changes in crop rotation were improvements in plows and animal harnessing. More land under cultivation spurred experimentation in the construction of plows. Peasants attached wheels to their plows, which made it easier for oxen to pull them through the heavier, wetter soil of northern Europe, and made it possible for a plow to move more quickly down a row – provided it had a speedy animal pulling it. Oxen are slow and unintelligent compared to horses, but peasants could not use horses to pull plows until they devised a different kind of harnessing than the strap that circled an ox's neck. With a harness resting on its shoulders instead of its neck, a horse could be used to plow, and horses could walk more quickly and work longer hours than oxen. They also required less guidance, since they understood verbal signals to turn or to stop. Heavier, wheeled plows pulled by suitably harnessed horses meant that peasants could work more land in a day than ever before. Whether an increase in population across western Europe, but particularly in the north, stimulated innovations or whether such innovations contributed to a rise in population, the cumulative effect of these changes in agriculture was apparent in the tenth century. Conditions in Europe were ripe for an economic and cultural upswing. Even before trade with the eastern Mediterranean increased starting in the twelfth century, trade and towns were on the rise. Travel was still dangerous, but merchants were willing to risk transporting goods over long distances. By the late thirteenth century, a few merchants from Italy had even reached China. Greater surpluses in crops meant people had more to sell at market. More people and goods led to regularly held markets in the most populated location in a region. It would be impossible to say whether trade gave rise to towns or vice versa. What is clear is that each fostered the other in conditions of greater social stability. Travel on trade routes increased, and some towns sprang up to provide rest and refreshment to traders. The distance between towns often corresponded to the distance that traders could cover in a day. Merchants kept their eyes open for customers with money to spend. The residences of kings, nobles, and powerful officials became sites of markets for local and long-distance traders. In Champagne, in northeastern France, six large annual markets attracted merchants from all over Europe in the twelfth century. Their different currencies prompted the first development of banking techniques. With the use of coins now the norm, money changers daily posted changing exchange rates so that merchants would know the worth of their coins in relation to the worth of other merchants' coins. By 1300, trade had transformed life for the better throughout western Europe.