In the Middle Ages, Catholic monks (particularly the Cistercians) were the most prominent viticulturists of the time period. Around this time, an early system of "Metayage" emerged in France with laborers ("Prendeur") working the vineyards under contractual agreements with the landowners ("Bailleur"). In most cases, the "prendeurs" were given flexibility in selecting their crop and developing their own vineyard practice. In northern Europe, the weather and climate posed difficulties for grape cultivation, so certain species were selected that better suited the environment. Most vineyards grew white varieties of grape, which are more resistant to the damp and cold climates. A few species of red grape, such as the Pinot Noir, were also introduced.