Danube? I think you mean the Rhine.
Yes, indeed. Cursed my hands and my eyes.
As for Merovingian Germania, maybe that's because regions were Germanic, before the Franks?
Maybe, and/or knowing regular waves of germanisation with migrants since Gallic or Roman times in countryside, eventually swallowing up Romance enclaves.
Giving the rarity of sources, the only real tool would be historical linguistics, but even there sources are rare and mostly appearing centuries earlier.
The only real linguistical source about Germanic speeches in Francia is the Strasbourg' Oath, and it seems we have a more or less artificial mix on Old High German bases.
Doesn't mean Franks had no linguistical influence at all (I think, but should check, they had an important role in dialectal distinction), but it might explain the disprencies.
Certain things might be there, but only have been written down later as a mark of distinction.
Thing is, we simply don't have anything about them, while they should be quite obvious, as typical, material culture. The fransisca is completly absent prior the Vth, either archeologically or by sources.
And most of what was considered as characteristic of Merovingians, such as funeral rites or political divisions (the "Frankish Kingdoms") are today mostly considered as at least heavily coming from Late Gallo-Roman/Roman structures or uses.
As for laws, we have quite enough sources pointing that they were made within Romania and with the help of Roman nobles (the Burgundic Law and the influence of Syagrius of Lyons, "New Solon" for Appolinarius).
Don't get me wrong : you had a real Germanic influence, that would be foolish to deny it, that particularly exerced its presence since the IIIrd century.
But what
characterised peoples as Franks from, say Alamans, whom ethnogensis was the product of their interaction with Romans, is largely absent archeologically or litterarily.
Eventually one can wonder if, considering that almost all made Franks "Franks" in latter period was a recent enough social construct, what made a Frank a Frank wasn't its integration into Barbarian political structures (that we agreed were determining in their ethnogenesis).
It goes as far as religion : Burgundians were Niceans before switching to Homeism, for exemple. Or, of course, histories of the origin that are largely coming from Aeneid, Bible or other basic sources of the time.
The myth of trojan origins of Franks is quite interesting on this regard : it reached a point where the myth made Franks not Germans, or at least not just Germans (and occulting totally their origins, you clearly mentioned above).
Frankish identity was an "ungoing project", a whole set of identitarian features by the Vth century, and while the anti-Romanism was quite a thing by the Carolingian period, Merovingian period was certainly less so, would it be by sheer political necessities.
I'll use the exemple of the
francisca* : absent before the Vth, appearing in the same time as an handful of other "ethnic" features, disappearing while the fusion of population is largely made.
*I know, again.
As for Charlemagne he probably didn't spoke Alemanic.
Germanic Frankish itself too partially underwent the High Germanic Consonant shift [/QUOTE]
Problem is that Frankish didn't lived on very long : I trust you on what Charlemagne could have spoken (I think, tough, that it may have been a Rheinish speech), but it likely couldn't have been old Frankish, expect speculating on the large survivance of a language that simply didn't appeared on sources since the Vth.
The language may have virtually disappeared as an everyday language by the VIth century, surviving mostly as a ceremonial one as in sentences in Salic Law. Simply said : we don't have anything past this point. (It's hardly a sole case, Gothic was barely used in Spain).
That everything remotly Germanic looking in French was labelled Frankish at some point isn't exactly a stellar proof. These Germanic influences can be attributed to a lot of Western Germanic peoples, including ones that never had the chance to form a state.
Does that means that Franks didn't had a direct cultural/linguistic influence? Of course not. But we can nuance it, giving the re-study of their presence and Germanic legacy.
apart from the Low Countries and adjacent areas. OTOH it didn't entail Alemannic or Bavarian,
the powerbase of the Carolingians was in the border region of Belgium, Germany and the Netherlands.
It fits too well with the map of Carolingian palaces during Charlemagne's reign to be entierly safe to me, in all honesty. These had vocation to form a power network for the empire, rather than to point a powerbase.
While present in Lower Rhine, Peppinids/Arnulfids (the latter took over the
sippe with the fiasco after Grimoald's misguided attempt) had a real importance on Rhineland proper : their familial network (Arnulf of Metz, for exemple but as well the aformentioned Agilofings of Bavaria), the political focus gaven to Alemania, Thuringia, etc., or the charges they recieved from Merovingians (Champagne, parts of Bourgogne).
Overall, I'm under the impression of a
sippe going from modern Wallonia up to modern Switzerland (not at all unrivaled as Hugobertides and Ethiconids can point) and with eventually more familial ties with Rhineland families than Flemish. It's no clear proof, but it makes me leaning towards a Rheinish speech that admittedly could be more likely Middle-High German than Alemanic.
I guess I overestimated its early medieval expansion that I tought reached Middle Rhine.