TRANSHUMANCE IS THE ancient custom of moving domestic animals from 1 grazing ground to another, as from lowlands to highlands, with the changing of seasons; sheep, cattle, and goats have all been involved in this annual domestic migration process. The origin of the word partially comes from the French transhumer, to move livestock seasonally. The purpose of transhumance is to move livestock to the cooler highlands to take advantage of freshly sprouted new grass. Animals were also moved from the lowlands up into the mountains to avoid the heat in the plains, particularly in France and Spain. After summering in the cool mountains, the process is reversed in late fall before snowfall makes passage difficult for the return trip. By the time flocks return, autumn rains in the lowland pastures have renewed growth to feed returning flocks. This tradition has been observed for centuries in . The Romans noted transhumance as an ancient Iberian tradition. Visigoths at the geographical limits of the Roman Empire passed their own laws to allow for free passage of flocks during the annual move. Moors introduced Merino sheep during the 8th century, and their Berber shepherding methods allowed Spain to gain a monopoly on the fine quality wool, which, over the last 6 centuries, has become 1 of its most important industries. Herds are moved early in the spring, both to take advantage of the fresh grass and to avoid the summer heat, but also because most farms do not have enough pasture for large flocks. For centuries, farmers have burned their fields after harvest to remove dead and depleted vegetation as well as to reduce the acidity of the soil. This custom promoted the regeneration of nutrient- rich grasslands for their animals, as well as fallow time for croplands to recover. Practices such as transhumance lessened the stress to the soil caused by overgrazing.