The Marcomanni were a Germanic tribal federation which inhabited Bohemia and other lands north of the Danube. They allied with the Suebi against the Roman Republic during the Gallic Wars of the 50s BC, and they eventually moved into the large lands once owned by the Boii. By 6 BC, their king Maroboduus had established a powerful kingdom which even the Roman Empire saw as a threat. During the 2nd century AD, Marcus Aurelius campaigned against the Marcomanni, fighting them for 14 years before dying in 180 AD; the Marcomannic Wars were only a limited success for Rome, as the Danube remained the Roman Empire's frontier. Under queen Fritigil, the Marcomanni adopted Christianity. They later joined the Suebi in their migration to the western Iberian Peninsula, and those who stayed behind became the ancestors of the Bavarii.