The Marcomanni were a Germanic people that established a powerful kingdom north of the Danube, somewhere near modern Bohemia, during the peak of power of the nearby Roman Empire. According to Tacitus and Strabo, they were Suebian.
It is believed their name may derive from Proto-Germanic *markō "border, boundary" (hence the English march or mark, meaning "frontier, border", as in the Welsh marches and the kingdom of Mercia) and *mann- (pl. *manniz) "man", *Markōmanniz, which would have been rendered in Latinised form as Marcomanni.
The Marcomanni first appear in historical records as confederates of the Suebi of Ariovistus fighting against Julius Caesar in Gaul (now France) after they had crossed the Rhine from what is now southern Germany. The exact position of their lands at the time is not known. The fact that their name existed before the Romans had territory near the Danube or Rhine raises the question of which border they lived near to explain their name. Their name may echo an earlier demarcation between the northern Germanic tribes of the Jastorf cultural circle and those of the maximum expansion of the Celts during the earlier and later Iron Age of La Tène dominance throughout Europe. Findings in the archaeological record show that they had pressed north with some influence as far as into Jutland, but they mostly remained separated in the south and settled in oppida over what is now Thuringia and Saxony along the Hercynian Forest, intrinsically connected to the major trade roads that went into the more evolved centres of Bohemia, Moravia and Silesia, which were then all still Celtic regions. It has been suggested that they may have lived near the confluence of the Rhine and Main Rivers in areas that had been inhabited but left deserted by the Helvetii and Taurisci. However, the historian Florus reports that Drusus erected a mound of their spoils during his campaign of 12–9 BC after he had defeated the Tencteri and Chatti, and before next turning to Cherusci, Suevi, and Sicambri.