Part of The Frankish Empire

Merovingian kingdom (481-751)

Numerous small Frankish kingdoms existed during the 5th century around Cologne, Tournai, Le Mans, Cambrai and elsewhere. After the fall of the Western Roman Empire, the Franks created an empire under the Merovingian kings and subjugated the other Germanic tribes. The Merovingian kings of the Germanic Franks conquered northern Gaul in 486 AD. Swabia became a duchy under the Frankish Empire in 496, following the Battle of Tolbiac; in 530 Saxons and Franks destroyed the Kingdom of Thuringia. In the 5th and 6th centuries the Merovingian kings conquered several other Germanic tribes and kingdoms. King Chlothar I (558–561) ruled the greater part of what is now Germany and made expeditions into Saxony, while the Southeast of modern Germany was still under influence of the Ostrogoths. Saxons inhabited the area down to the Unstrut River.

Regions of the Frankish Empire were placed under the control of autonomous dukes of mixed Frankish and native blood. Frankish Colonists were encouraged to move to the newly conquered territories. While the local Germanic tribes were allowed to preserve their laws, they were pressured into becoming Christians.

The German territories became part of Austrasia (meaning "eastern land"), the northeastern portion of the Kingdom of the Merovingian Franks. As a whole, Austrasia comprised parts of present-day France, Germany, Belgium, Luxembourg and the Netherlands. After the death of the Frankish king Clovis I in 511, his four sons partitioned his kingdom including Austrasia. Authority over Austrasia passed back and forth from autonomy to kingly subjugation, as Frankish lands were alternately united and subdivided by the Merovingian kings.

In 718, Charles Martel, the Franconian Mayor of the Palace, made war against Saxony because of its help for the Neustrians. His son Carloman started a new war against Saxony in 743, because the Saxons gave aid to Duke Odilo of Bavaria.

Mask reliquary of
Charles the Great
in Aachen Cathedral

In 751, Pippin III, Mayor of the Palace under the Merovingian king, himself assumed the title of king and was anointed by the Church. Now the Frankish kings were set up as protectors of the pope, and Charles the Great launched a decades-long military campaign against their heathen rivals, the Saxons and the Avars. The campaigns and insurrections of the Saxon Wars lasted from 772 to 804. The Saxons and Avars were eventually overwhelmed, the people were forcibly converted to Christianity, and the lands were annexed by the Carolingian Empire.

Carolingian empire (751-843)

After the death of Frankish king Pepin the Short in 768 AD, his son Charles consolidated his control over his kingdom and became known as "Charles the Great" or "Charlemagne." From 771 until his death in 814, Charlemagne extended the Carolingian empire into northern Italy and the territories of all west Germanic peoples, including the Saxons and the Baiuvarii (Bavarians). In 800, Charlemagne's authority was confirmed by his coronation as Holy Roman Emperor by the pope on Christmas Day in Rome. Imperial strongholds (Kaiserpfalzen) became economic and cultural centres, of which Aachen was the most famous.

Fighting among Charlemagne's grandchildren caused the Carolingian empire to be partitioned into several parts by the Treaty of Verdun (843), the Treaty of Meerssen (870), and the Treaty of Ribemont. The German region developed out of the East Frankish kingdom, East Francia.

References: Wikipedia