Marcomnni (Ger., men of the marches or borders), an ancient German people of Suevic race. They appear to have originally dwelt in the regions of the Main and Neckar in S. W. Germanv, whence thev followed Ariovistus across the Rhine on his invasion of Gaul, and afterward their own chief Maroboduus into the land of the Boii, which embraced parts of modern Bohemia and Bavaria. Having subdued that people, they established a powerful kingdom N. of the Danube, which soon became involved in wars with the Cherusci, and afterward with the Romans. Their longest and bloodiest war was that waged in alliance with the Quadi, Hermunduri, Narisci, and other German tribes, against the emperor Marcus Aure-The latter having died (180) in Vindo-bona (Vienna) on his last expedition against them, his son and successor Commodus hastened to conclude by purchase a shameful peace with the barbarians. In the 3d and 4th centuries the Marcomanni made some new incursions into the Danubian provinces of the Romans, but during the following great migration of northern nations they finally disappeared from history.