The Rheinhessen is the largest of Germany's wine regions, with over 25,000 hectares under vine. Approximately 70% of the production is white, particularly from the Riesling and Müller-Thurgau grape varieties, while much of the red wine production is from the Dornfelder grape. On the one hand, the Rheinhessen has a reputation as a bulk wine producer, exploiting the high yields to drive mass-markets. On the other, the region is home to some of the most exciting and dynamic winegrowers, who are exploring low yields, individual vineyard sites and alternative methods of farming, in the search for ever better quality. The Rheinhessen begins near Worms in the south - where the key villages include Osthofen and Bechtheim - before the River Rhine continues north to Bingen and then up to Mainz, to meet the Rheingau region. The presence of the river is the greatest influence on the region, both moderating temperatures in the summer and preventing winter frosts. The Rheinhessen is a sheltered valley, but is generally gentler in relief than the Rheingau, with the exception of the vineyards between Oppenheim and Nackenheim, which are known as the 'Rhine Terrace' due to their steep slopes.