The Alemanni were an ethnic group of Germanic tribes that did not belong to the old tribes, such as those listed by Tacitus for the 1st century AD, but were newly formed in the course of the 3rd century. The historiographer Agathias of Myrina, writing in the 6th century, has this type of tribal formation in mind when he describes the Alemanni as a "grouped and mixed people" and adds: "And this is precisely what their name expresses". "All men", "all kinds of people" - this meaning of the word can still be understood today.

It was not the idea of a common ancestry, but a political will directed towards a common goal that established the identity of the Alemanni. This is also evident from the fact that at the same time, other Germanic groups besides the Alemanni reorganized themselves into such tribes. It is striking that these new groupings obviously focused on Roman provinces as the targets of their political activities. The Franks saw themselves as being at odds with the Roman province of Germania Secunda, while the Saxons regarded Britain and the Jutungen Rhaetia, which only appeared episodically, as their desirable targets. Accordingly, the Alemanni focused their political interest on the province of Germania Prima, formerly Upper Germania, initially as a target area for raids and plundering, but ultimately also as a possible expansion area in terms of land acquisition and settlement.

The Alemanni achieved their first great success when they were able to take possession of the territories on the right bank of the Rhine in the province of Germania prima soon after the middle of the 3rd century. After the collapse of the Roman military organization at the Upper Germanic Limes, the so-called Dekumatland (agri decumates) came under the rule of the Alemanni and with it the area of the city of Wiesbaden. Here, of course, the Alemanni's claim to rule was in competition with Roman efforts to control the right bank of the Rhine in front of the provincial capital of Mogontiacum/Mainz as far as possible, and indeed to maintain this bridgehead as part of their own province.

From the political interests of the Alemanni in Germania prima described above, it is clear that their efforts must have been particularly focused on the provincial capital, and that the right bank of the Rhine at Mogontiacum/Mainz, including the old Aquae Mattiacae, must therefore have been of primary strategic importance to the Alemanni tribe. This is confirmed by both written and archaeological sources.

The Roman historian Ammianus Marcellinus, for example, reports in connection with a Roman campaign in 371 AD of an Alemannic tribe (gens ... Alamannica) called Bukinobantes, which means "inhabitants of the beech forest". This tribe was located contra Mogontiacum, i.e. opposite Mainz, on the outskirts of Mainz. However, it can also be understood as "in a frontal position against Mainz", which indicates the political interests of those Bucinobantes.

This campaign was personally led by the Roman Emperor Valentinian I and was directed against a king of the Bukinobantes named Makrian. The vanguard of the Roman army under the commander Severus first advanced against Wiesbaden (contra Mattiacas Aquas), which is the last mention of the old Roman name of Wiesbaden in ancient literature.

Makrian was able to escape from Roman control by fleeing; in his place, a certain Fraomar was installed as tribal king, but he was unable to hold on in the long term ... The events described in detail by Ammianus Marcellinus shed light on the power relations in the territory between the Taunus ridge and the mouth of the Main, which was contested between the Romans and the Alemanni.

Moreover, Valentinian's campaign was apparently in retaliation for a raid on Mainz, which an Alemannic tribal leader (regalis) named Rando had undertaken three years earlier. He had seized the opportune moment when the city had just been stripped of its troops and when a Christian holiday, presumably Easter, was being celebrated there. Rando was able to capture Mainz with a band of marauders and then departed with rich booty. According to Ammianus Marcellinus, he had planned this coup long in advance (diu praestruens, quod cogitabat); it is therefore unlikely that he suddenly emerged from the depths of Germania, but had had his eye on the object of his desire for some time, most likely from Aquae Mattiacae.

This news from the reign of Emperor Valentinian sheds light on the importance of the Wiesbaden region for both the Romans and the Alemanni in Late Antiquity. The archaeological findings also correspond to this assessment. The attempt to protect Roman interests is manifested in the construction of the Heidenmauer, but ultimately failed.

The opponents of the Romans, the Alemanni, can be proven archaeologically in a different way. It should be noted that the archaeological record for the early Alemannic period in the area of the former Dekumatland is generally extremely poor:

Not only are settlement finds rare, but the extremely numerous burial finds that have survived from the preceding Roman period as well as from the subsequent Merovingian period are downright rare; only here and there do individual burials or at best minimal burial groups make an appearance. Against this background, the find tradition for the urban area of Wiesbaden seems almost abundant.

A double grave of a man and a woman was found within the long-abandoned stone fort of the 1st century AD. Further graves were found not far away on the south-eastern slope of the Michelsberg, both outside and inside the Heidenmauer. Furthermore, individual graves were found in the area of Kirchgasse/Friedrich-/Luisenstraße, presumably with a topographical reference to the old Roman cemetery located there. Further away, a single grave was found in Waldstraße.

In all cases, the dead were buried unburned (body graves). The men were buried with weapons such as long swords, battle axes and lances, while the women were buried with all kinds of jewelry such as necklaces made of glass and amber beads, necklaces and earrings, hairpins and, above all, fibulae. A special form of these garments, namely brooches made of silver or bronze sheet with a diamond-shaped base, are referred to in archaeological terminology as "Wiesbaden-type brooches", precisely because they first appeared in Wiesbaden in a distinctive form. In general, the Early Alemannic grave finds from Wiesbaden are considered an ideal example of the Early Alemannic find horizon due to their comparatively large number and the fact that they were published by Eduard Brenner as early as 1911.

However, as far as the location and form of the dwellings of the Alemanni buried on Michelsberg and the other sites are concerned, there is a lack of tangible archaeological evidence. It would not be wrong to assume that they were in the area of the springs, where the settlement areas of the Roman period were already located (Roman period). The fact that a settlement layer from the Early Alemannic period was discovered outside the immediate Wiesbaden urban area, namely during the construction of the ICE route near Breckenheim, should only be mentioned in passing.

In many cases, the early medieval period of the Frankish and Merovingian periods was able to seamlessly follow on from the conditions of the Early Alemannic period (late antiquity and the Migration Period). In the core area of Wiesbaden, not only did the settlement area remain constant, but the burial site on Schwalbacher Straße also recognizably ties in with the previously used cemetery area. Of the early Christian gravestones found in this area in the form of individual finds, the oldest evidence of Christianity in Wiesbaden, one or two could have been erected as early as the Late Antique/Alemannic period. Finally, some of the terraced cemeteries in the wider area around the Wiesbaden core settlement, which were mainly documented in the early Middle Ages, with their oldest burials date back to the early Alemannic period(Schierstein and Kostheim).