(...) In the Middle Ages, Champagne was famous for its great fairs, held at Troyes (the capital), Provins, Lagny-sur-Marne, and Bar-sur-Aube. Merchants from all over western Europe met six times each year. Their laws regulating trade had a profound influence on later commercial customs; the troy weight for precious metals is still used. Prosperity was accompanied by cultural brilliance, culminating in the work of Chrétien de Troyes and in the Gothic cathedral at Reims. The county of Champagne had passed to the counts of Blois in the 11th cent.; the main branch held Champagne after 1152. The domain was greatly extended; large parts of France, including Blois, Touraine, and Chartres, were dependent upon the Champagne counts. Most famous of the counts was Thibaut IV, who in 1234 inherited the crown of Navarre from his uncle Sancho VII. In 1286 the daughter and heir of Henry III, Count of Champagne and King of Navarre, married Philip IV of France. When their son ascended the French throne (as Louis X) in 1314, Champagne was incorporated into the royal domain. The bishoprics of Reims and Langres were added later. Champagne declined in prosperity thereafter; however, the enduring popularity of its sparkling wine, which was developed at the end of the 17th cent., somewhat revitalized its economy. More recently, efforts have been made to reforest the area and reclaim it from erosion.