Farther east, descendants of Lusatian and Silesian peasants still use the vernacular of their ancestors in the upland formed by the Iser Gebirge and the Riesen Gebirge. In modern times the valleys of these mountains yield a steady stream of German-speaking inhabitants to the industrial towns of the southern plain. The German workingman’s competition with his Bohemian fellow laborer is keen in this district, but it has not been marked by a notable advance of the Teutonic idiom. Linguistically the Bohemians and Moravians form a unit hemmed in by Germans on all sides except the east, where they abut against their Slovak kinsmen. Community of national aspirations, under the leadership of the Bohemian element, is generally ascribed to these three Slavic groups. The union has been fostered by the lack of a literary language among Moravians, who have adopted the Bohemian alphabet and style. With the Slovaks[144] inferiority of numbers helped the spread of the Bohemian language and literature. The Czech linguistic area presents homogeneity of composition which is seldom encountered in other parts of Austria-Hungary. Intermingling of Slavic and Teutonic elements has been slight in this advanced strip of Slavdom. Overlapping of German is met in belts generally parallel to the political divide. It is particularly noticeable in the angle formed by the junction of the Böhmerwald and Erzgebirge near the western linguistic divide, where it almost attains the town of Pilsen.[145] Beyond, in a northerly direction, the volcanic area characterized by thermal springs lies within the German line. Reichenberg, a strenuous center of Teutonism, maintains easterly and westerly prongs of German in the Iser-Riesen uplifts and the Elbe valley, respectively. The German of Silesia spreads into Moravia along the Zwittau-Olmütz-Neu Titschen line. A short stretch of the linguistic boundary coincides with the political frontier in the neighborhood of Taus, but the rest of the southern Böhmerwald overlooking Bohemian levels is German in speech from the crests to the zone in which widening of the valleys becomes established. The disappearance of this mountainous chain, in southern Moravia, coincides with a southerly extension of Czech in the valley of the March. Contact with Slovak dialects begins in the Beskid area.