A large portion of the vineyards is located in hilly terrain on sunny slopes, for which the locals use the term Sori. DThe most important wine-growing regions are Asti, Carema, Canavese, Caluso, the Vercelli and Novara hills, as well as the sites considered to bet he best, the hills of Monferrato and Langhe near Alba. There are more than a hundred permitted grape varieties (indeed there were almost 400 varieties according to a census in the 19th century), many of these are indigenous, and quite a few of them are of French origin. The leading red variety is Barbera, with around 50% of the vineyard area, which is the basic ingredient for many of the everyday wines. The other important red varieties are Bonarda, Brachetto, Cortese, Dolcetto, Freisa, Grignolino, Nebbiolo and Malvasia. The leading white varieties are Arneis; Cortese, Erbaluce and Moscato Bianco. International varieties such as Cabernet Franc, Cabernet Sauvignon, Chardonay, Pinot Bianco, Pinot Grigio and Pinot Noir are gaining in importance. Apart from Tuscany, Piemont supplies most of the top-quality wines in Italy, and there is a constant rivalry as to which deserves to be the leading wine-growing region. Red wines account for more than 75% of the total production, and the fame of these wines is based mainly on the two exceptional wines made from the Nebbiolo grape, Barbaresco and Barolo. There was a French influence here, too, as the initiator of these two wines was the French oenologist Louis Oudart. In recent times, three of the most important figures have been the famous winemakers Angelo Gaja, Giacosa Bruno and Giacomo Bologna on his Braida estate. Piemont plays a leading role in Italy in several respects. The region has the largest number of DOC zones in Italy – more than 50 – which account for around a quarter of the wine production. However, most of the DOC wines are white. Piemont also has undisputably the largest number of DOCG wines, namely 10. In addition, this is the region in which the greatest volume of sparkling wines is produced. The region is also the source of vermouth for Italy and the whole world, this is where vermouth was „invented”. The DOC zones are: