The name is Latinized from the ethnonym *Bajōwarjōz, meaning "citizens of Bohemia" from Proto-Germanic *Bajōhaimaz (Boiohaemum, Bohemia), meaning "Boii home", which was a term already mentioned by Tacitus in his Germania at the end of the 1st century AD, by which time parts of the Celtic Boii had already left the area,[4] leaving it to be dominated by Suevic Germanic groups in close contact with the Romans, such as the Marcomanni in what is now the Czech Republic, and their neighbours the Hermunduri and Varisci in what is now northern Bavaria.

The timing comes after the period when the neighbouring Alamanni (to the west) and Thuringians (to the north) had come under Frankish hegemony, and in Italy the kingdoms of Theoderic and Odoacer had come to an end, creating a new power vacuum in the Alpine region.

Their legal system shows heavy Roman influence, and their unification appears to have been under a Duke installed by the Franks (Old Bavarian law codes refer to five main lineages).

But also more northern groups had moved along the Elbe from the direction of the North Sea, as did some Saxons who joined the Lombards, and possibly the Heruls.

Also entering the area, more contemporary with the Bavarians and Lombards, were Slavs, who particularly settled the Upper Palatinate as well as around Regensburg itself (distr.

[7][8][9][10] Neighboring the emerging Bavarian people in the 6th to 7th centuries were the Alamanni to the west (with the river Lech as boundary, which remains a dialectal division today), and Thuringians to the north, both dominated to some extent by the Franks as were the Bavarians (in the late 7th century however, there was a period where Radulf, King of Thuringia rebelled and some independence was returned to these three regions for a while).

Bavaria within the Carolingian Empire was bordering on Swabia in the west, Thuringia in the north, Lombardy in the south and Slavic Carinthia in the east.

The kingdom's territory fluctuated greatly over the following years, eventually fixed at the Treaty of Paris (1814), which established most of what remain the borders of the modern state.