Looking to to the great moravian expansion I think we should talk about the Ostsiedlung or Drang nach Osten. As always, some maps:
Better one here: https://upload.wikimedia.org/wikipedia/commons/b/bd/Deutsche_Ostsiedlung.png
Talus, you said that the Moravian took Regensburg, right? So their western border os the Naab River? Looking at the light orange part in the 2° map that was the area of german expansion negated by the pod, the dark orange was pre pod. The Ostsiedlung proper really picks up steam around the year 1000.
Charlemagne hasnt been around to stablich this https://en.wikipedia.org/wiki/Danish_March , so the red area of holstein remains Saxon, but with how thing are going it's probably under either Danish and/or slavic threat.
After the X century the Ostsiedlung will likely happen just because of the population presure from the german side:
"Population growth during the High Middle Ages stimulated movement of peoples from the Rhenish, Flemish, and Saxon territories of the Holy Roman Empire eastwards into the less-populated Baltic region and Poland. These movements were supported by the German nobility, the Slavic kings and dukes, and the medieval Church. The majority of this settlement took place at the expense of Polabian Slavs and pagan Balts (see Northern Crusades).
The future state of Prussia, named for the conquered Old Prussians, had its roots largely in these movements. As the Middle Ages came to a close, the Teutonic Knights, who had been invited to northern Poland by Konrad of Masovia, had assimilated and forcibly converted much of the southern Baltic coastlands."
Of course, as the wiki on Ostsiedlung notes, the process is inceparable from the politics of Charlemagne and the East France and HRE rulers, and of course the convertion of the slavs to christianity (really needed for them to let lots of christian germans into their lands).
"The Slavs living within the reach of Francia (later the Holy Roman Empire) were collectively called Wends or "Elbe Slavs". They seldom formed larger political entities, but rather constituted various small tribes, dwelling as far west as to a line from the Eastern Alps and Bohemia to the Saale and Elbe rivers. As the Frankish Empire expanded, various Wendish tribes were conquered or allied with the Franks, such as the Obotrites, who aided the Franks in defeating the West Germanic Saxons. The conquered Wendish areas were organized by the Franks into marches (German: Marken, meaning "border" or "border lands" in German), which were administered by an entrusted noble who collected the tribute, reinforced by military units. The establishing of marches was also accompanied by missionary efforts.
...
In most cases, the tribes of the marches were not stable allies of the empire. Frankish kings initiated numerous, yet not always successful, military campaigns to maintain their authority.
...
Under the rule of King Louis the German of East Francia and of Arnulf of Carinthia, the first waves of settlement were led by Franks and Bavarii, and reached the area of what is today Slovakia and what was then Pannonia (present-day Burgenland, Hungary, and Slovenia). These pioneering settlers were Catholics.
Although the first settlements led by the Franks and Bavarii followed the conquest of the Sorbs and other Wends in the early 10th century, and other campaigns by Holy Roman Emperors made migration possible, the beginning of a continuous Ostsiedlung is usually dated to around the 12th century."
For this to work, the Wends had to be beaten quite hard:
"In 983, the Polabian Slavs in the Billung and Northern Marches stretching from the Elbe to the Baltic Sea succeeded in a rebellion against the political rule and Christian mission of the Empire. In spite of their new-won independence, the Obotrites, Rani, Liutizian and Hevelli tribes were soon faced with internal struggles and warfare as well as raids from the newly constituted and expanding Piast dynasty (early Polish) state from the east, Denmark from the north and the Empire from the west, eager to reestablish her marches.
Weakened by ongoing internal conflicts and constant warfare, the independent Wendish territories finally lost the capacity to provide effective military resistance. From 1119 to 1123, Pomerania invaded and subdued the northeastern parts of the Liutizian lands. In 1124 and 1128, Wartislaw I, Duke of Pomerania, at that time a vassal of Poland, invited bishop Otto of Bamberg to Christianize the Pomeranians and Liutizians of his duchy. In 1147, as a campaign of the Northern Crusades, the Wendish Crusade was mounted in the Duchy of Saxony to retake the marches lost in 983. The crusaders also headed for Pomeranian Demmin and Szczecin (Stettin), despite these areas having already been successfully Christianized.
After the Wendish crusade, Albert the Bear was able to establish the Brandenburg march on approximately the territory of former Northern March, which since 983 had been controlled by the Hevelli and Liutizian tribes, and to expand it. The Havelberg bishopric was set up again to Christianize the Wends.
In 1164, after Saxon duke Henry the Lion finally defeated rebellious Obotrites and Pomeranian dukes in the Battle of Verchen, the Pomeranian duchies of Demmin and Stettin became Saxon fiefs, as did the Obodrite territory, which became known as Mecklenburg after its main "burg", fortified settlement. After Henry the Lion lost an internal struggle with Emperor Frederick I, Mecklenburg and Pomerania became part of the Holy Roman Empire in 1181."
Of course it's posible for the slavs to assimilate the germans, they did in otl:
"Colonization was the pretext for assimilation processes that went on for centuries. Assimilation occurred in both directions - depending on the region, either the German speakers, or the local non-Germanic population, was assimilated.
The Polonization process of Germans who had settled since the 13th century in Poland, in towns like Kraków (Krakau, Cracow) and Poznań (Posen) in the midst of Polish lands, lasted about two centuries. They constituted a patriciate which was not able to continue its isolated position without a continuation of newcomers from German lands. The Sorbs over time also assimilated German settlers in their midst, yet at the same time other Sorbs were themselves assimilated by the surrounding German-speaking population. Many Central and Eastern European towns remained for some centuries multi-ethnic melting pots.[33] "
As you can guess, in order to succesfully assimilate the germans slavs will need two things: strong states and (probably) to share religion with the germans. The social and church organization of christianity and islam will make the germans imposible (and probably not desirable) to assimilate by pagan slavs.
The settlers:
"The vast majority of the settlers were speakers of a variety of German dialects. In the northern zones Low German, at that time varieties of Lower-Saxonian, but also of early Netherlandish, that is to say, in modern terms, Dutch and Flemish. Next to these also Frisian. In the central zones speakers of Thuringian en Upper-Saxonian participated. In the southern zones speakers of East Frankish and Bavarian tongues were dominant. Significant numbers of Dutch, Frisians and Flemish as well as (though to a lesser extent) Danes, Scots or local Wends and (French speaking) Walloons also participated. The settlers were mostly landless younger children of noble families who could not inherit property. Entrepreneur-adventurers, often from lower-noble descent, called locators, played a recruiting, negotiating and co-ordinating role and established new villages, juridically and geo-physically. Of course, outlaws took the opportunity to escape but they were not appreciated because success depended upon discipline and solidarity.[32]
The settlers migrated in nearly straight West-to-East lines. As a result, the Southeast was settled by South Germans (Bavarians, Swabians), the Northeast by Saxons (in particular those from Westphalia, Flanders, Holland, and Frisia, while central regions were settled by Franks. As a result, the different German dialect groups expanded eastward along with their bearers, the "new" Eastern forms only slightly differing from their Western counterparts.
Settlers were invited by local secular rulers, such as dukes, counts, margraves, princes and (only in a few cases due to the weakening central power) the king. Among them the Slavic dukes (piasts) and kings. Also, settlers were invited by religious institutions such as monasteries and bishops, who had become mighty land-owners in the course of Christian mission. Often, a local secular ruler would grant vast woodlands and wilderness and a few villages to an order like the Cistercian monks, who would erect an abbey, call in settlers and cultivate the land.
The settlers were granted estates and privileges. Settlement was usually organised by a so-called Lokator (allocator of land), who was granted an important position such as the inheritable position of the village elder (Schulte or Schulze). Towns were founded and granted German town law. The agricultural, legal, administrative, and technical methods of the immigrants, as well as their successful proselytising of the native inhabitants, led to a gradual transformation of the settlement areas, as former linguistically and culturally Slavic areas became Germanised."
The germans did had a heavy impact on eastern europe so if they don't go their absence will be felt: https://en.wikipedia.org/wiki/Ostsiedlung#Rural_development
Better one here: https://upload.wikimedia.org/wikipedia/commons/b/bd/Deutsche_Ostsiedlung.png
Talus, you said that the Moravian took Regensburg, right? So their western border os the Naab River? Looking at the light orange part in the 2° map that was the area of german expansion negated by the pod, the dark orange was pre pod. The Ostsiedlung proper really picks up steam around the year 1000.
Charlemagne hasnt been around to stablich this https://en.wikipedia.org/wiki/Danish_March , so the red area of holstein remains Saxon, but with how thing are going it's probably under either Danish and/or slavic threat.
After the X century the Ostsiedlung will likely happen just because of the population presure from the german side:
"Population growth during the High Middle Ages stimulated movement of peoples from the Rhenish, Flemish, and Saxon territories of the Holy Roman Empire eastwards into the less-populated Baltic region and Poland. These movements were supported by the German nobility, the Slavic kings and dukes, and the medieval Church. The majority of this settlement took place at the expense of Polabian Slavs and pagan Balts (see Northern Crusades).
The future state of Prussia, named for the conquered Old Prussians, had its roots largely in these movements. As the Middle Ages came to a close, the Teutonic Knights, who had been invited to northern Poland by Konrad of Masovia, had assimilated and forcibly converted much of the southern Baltic coastlands."
Of course, as the wiki on Ostsiedlung notes, the process is inceparable from the politics of Charlemagne and the East France and HRE rulers, and of course the convertion of the slavs to christianity (really needed for them to let lots of christian germans into their lands).
"The Slavs living within the reach of Francia (later the Holy Roman Empire) were collectively called Wends or "Elbe Slavs". They seldom formed larger political entities, but rather constituted various small tribes, dwelling as far west as to a line from the Eastern Alps and Bohemia to the Saale and Elbe rivers. As the Frankish Empire expanded, various Wendish tribes were conquered or allied with the Franks, such as the Obotrites, who aided the Franks in defeating the West Germanic Saxons. The conquered Wendish areas were organized by the Franks into marches (German: Marken, meaning "border" or "border lands" in German), which were administered by an entrusted noble who collected the tribute, reinforced by military units. The establishing of marches was also accompanied by missionary efforts.
...
In most cases, the tribes of the marches were not stable allies of the empire. Frankish kings initiated numerous, yet not always successful, military campaigns to maintain their authority.
...
Under the rule of King Louis the German of East Francia and of Arnulf of Carinthia, the first waves of settlement were led by Franks and Bavarii, and reached the area of what is today Slovakia and what was then Pannonia (present-day Burgenland, Hungary, and Slovenia). These pioneering settlers were Catholics.
Although the first settlements led by the Franks and Bavarii followed the conquest of the Sorbs and other Wends in the early 10th century, and other campaigns by Holy Roman Emperors made migration possible, the beginning of a continuous Ostsiedlung is usually dated to around the 12th century."
For this to work, the Wends had to be beaten quite hard:
"In 983, the Polabian Slavs in the Billung and Northern Marches stretching from the Elbe to the Baltic Sea succeeded in a rebellion against the political rule and Christian mission of the Empire. In spite of their new-won independence, the Obotrites, Rani, Liutizian and Hevelli tribes were soon faced with internal struggles and warfare as well as raids from the newly constituted and expanding Piast dynasty (early Polish) state from the east, Denmark from the north and the Empire from the west, eager to reestablish her marches.
Weakened by ongoing internal conflicts and constant warfare, the independent Wendish territories finally lost the capacity to provide effective military resistance. From 1119 to 1123, Pomerania invaded and subdued the northeastern parts of the Liutizian lands. In 1124 and 1128, Wartislaw I, Duke of Pomerania, at that time a vassal of Poland, invited bishop Otto of Bamberg to Christianize the Pomeranians and Liutizians of his duchy. In 1147, as a campaign of the Northern Crusades, the Wendish Crusade was mounted in the Duchy of Saxony to retake the marches lost in 983. The crusaders also headed for Pomeranian Demmin and Szczecin (Stettin), despite these areas having already been successfully Christianized.
After the Wendish crusade, Albert the Bear was able to establish the Brandenburg march on approximately the territory of former Northern March, which since 983 had been controlled by the Hevelli and Liutizian tribes, and to expand it. The Havelberg bishopric was set up again to Christianize the Wends.
In 1164, after Saxon duke Henry the Lion finally defeated rebellious Obotrites and Pomeranian dukes in the Battle of Verchen, the Pomeranian duchies of Demmin and Stettin became Saxon fiefs, as did the Obodrite territory, which became known as Mecklenburg after its main "burg", fortified settlement. After Henry the Lion lost an internal struggle with Emperor Frederick I, Mecklenburg and Pomerania became part of the Holy Roman Empire in 1181."
Of course it's posible for the slavs to assimilate the germans, they did in otl:
"Colonization was the pretext for assimilation processes that went on for centuries. Assimilation occurred in both directions - depending on the region, either the German speakers, or the local non-Germanic population, was assimilated.
The Polonization process of Germans who had settled since the 13th century in Poland, in towns like Kraków (Krakau, Cracow) and Poznań (Posen) in the midst of Polish lands, lasted about two centuries. They constituted a patriciate which was not able to continue its isolated position without a continuation of newcomers from German lands. The Sorbs over time also assimilated German settlers in their midst, yet at the same time other Sorbs were themselves assimilated by the surrounding German-speaking population. Many Central and Eastern European towns remained for some centuries multi-ethnic melting pots.[33] "
As you can guess, in order to succesfully assimilate the germans slavs will need two things: strong states and (probably) to share religion with the germans. The social and church organization of christianity and islam will make the germans imposible (and probably not desirable) to assimilate by pagan slavs.
The settlers:
"The vast majority of the settlers were speakers of a variety of German dialects. In the northern zones Low German, at that time varieties of Lower-Saxonian, but also of early Netherlandish, that is to say, in modern terms, Dutch and Flemish. Next to these also Frisian. In the central zones speakers of Thuringian en Upper-Saxonian participated. In the southern zones speakers of East Frankish and Bavarian tongues were dominant. Significant numbers of Dutch, Frisians and Flemish as well as (though to a lesser extent) Danes, Scots or local Wends and (French speaking) Walloons also participated. The settlers were mostly landless younger children of noble families who could not inherit property. Entrepreneur-adventurers, often from lower-noble descent, called locators, played a recruiting, negotiating and co-ordinating role and established new villages, juridically and geo-physically. Of course, outlaws took the opportunity to escape but they were not appreciated because success depended upon discipline and solidarity.[32]
The settlers migrated in nearly straight West-to-East lines. As a result, the Southeast was settled by South Germans (Bavarians, Swabians), the Northeast by Saxons (in particular those from Westphalia, Flanders, Holland, and Frisia, while central regions were settled by Franks. As a result, the different German dialect groups expanded eastward along with their bearers, the "new" Eastern forms only slightly differing from their Western counterparts.
Settlers were invited by local secular rulers, such as dukes, counts, margraves, princes and (only in a few cases due to the weakening central power) the king. Among them the Slavic dukes (piasts) and kings. Also, settlers were invited by religious institutions such as monasteries and bishops, who had become mighty land-owners in the course of Christian mission. Often, a local secular ruler would grant vast woodlands and wilderness and a few villages to an order like the Cistercian monks, who would erect an abbey, call in settlers and cultivate the land.
The settlers were granted estates and privileges. Settlement was usually organised by a so-called Lokator (allocator of land), who was granted an important position such as the inheritable position of the village elder (Schulte or Schulze). Towns were founded and granted German town law. The agricultural, legal, administrative, and technical methods of the immigrants, as well as their successful proselytising of the native inhabitants, led to a gradual transformation of the settlement areas, as former linguistically and culturally Slavic areas became Germanised."
The germans did had a heavy impact on eastern europe so if they don't go their absence will be felt: https://en.wikipedia.org/wiki/Ostsiedlung#Rural_development
Ostsiedlung - Wikipedia
en.wikipedia.org