The Thuringians do not appear in classical Roman texts under that name, but some have suggested that they were the remnants of the Suebic Hermanduri, the last part of whose name (-duri) could represent corrupted (-thuri) and the Germanic suffix -ing, suggests a meaning of "descendants of (the duri)". This people were living near the Marcomanni. Tacitus in his "Germania", describes their homeland as being where the Elbe starts, but also having colonies at the Danube and even within the Roman province of Rhaetia.
Claudius Ptolemy mentions neither the Hermunduri nor the Thuringians in his geography but instead the Teuriochaemae, living in just north of the Sudetes mountains, thought to be the Erzgebirge. These may also be connected to later Thuringians. ("Chaemae" may represent a version of the Germanic word for "home". Ptolemy also mentions a people called the Bainochaimai to the west of the Elbe. He also apparently spells the name of the Chamavi in a similar way.) The formation of this people may have had also been influenced by two longer-known tribes more associated with the eastern bank of the lower Elbe river, northeast of Thuringia, because the Carolingian law code written for them was called the "law of the Angles and Varini that is the Thuringians". Much earlier, Tacitus in his "Germania", for example, had grouped these two tribes among the more distant Suebic tribes, living beyond the Elbe, and near a sea where they worshiped Herthus. (Pliny the Elder had listed the Varini as a Vandalic, or East Germanic tribe, rather than Suebian.) These two tribes are among Germanic groups known to have been found north of the Danube in this period. Procopius in his "Gothic Wars" describes the land of the Varini as being south of the Danes, but north of the Slavs, who were in turn north of unfarmed lands which lay north of the Danube. Procopius describes a marriage alliance between the Angles of Britain and the Varni in the 6th century.
The name of the Thuringians appears to be first mentioned in the veterinary treatise of Vegetius, written early in the 5th century. Walter Pohl has also proposed that they may be the same as the Turcilingi (or Torcolingi) who were one of the tribes near the middle Danube after the collapse of the empire of Attila, under whom they had apparently all been. They are specifically associated with Odoacer, who later became King of Italy, and are sometimes thought to be a part of the Scirii. Other tribes in this region at the time included the Rugii and the Heruls. Sidonius, in his 7th poem, explicitly lists them among the allies who fought under Attila when he entered Gaul in 451. During the reign of Childeric I, Gregory of Tours and Fredegar record that the Frankish King married the runaway wife of the King of the Thuringians, but the story may be distorted. (For example, the area of Tongeren, now in Belgium, may have been intended.)
More clearly, correspondence is recorded with a kingdom of Thuringians by Procopius and Cassiodorus during the reigns of Theoderic the Great (454-526) and Clovis I (approx. 466-511), after the downfall of Attila and Odoacer.
The Thuringii established an empire in the late 5th century. It reached its territorial peak in the first half of the 6th before it was conquered by the Franks in 531–532. Examination of Thuringian grave sites reveal cranial features which suggest the strong presence of Hunnic women or slaves, perhaps indicating that many Thuringians took Hunnic wives or Hunnic slaves following the collapse of the Hunnic Empire. There is also evidence from jewellery found in graves that the Thuringians sought marriages with Ostrogothic and Lombard women. Under the leadership of Alboin, a large group of Thuringii joined the Lombards in their migration into Italy. The Lombard king Agilulf (590–616) was of Thuringian descent.
After their conquest, the Thuringii were placed under Frankish duces (dukes), but they rebelled and established themselves independently again by the late 7th century under Radulf. Towards the end of this century, parts of Thuringia came under Saxon rule.
By the time of Charles Martel and Saint Boniface, they were again subject to the Franks and ruled by Frankish dukes with their seat at Würzburg in the south. Under Martel, the Thuringian dukes' authority was extended over a part of Austrasia and the Bavarian plateau. The valleys of the Lahn, Main, and Neckar rivers were included. The Naab formed the south-eastern border of Thuringia at the time. The Werra and Fulda valleys were within it also and it reached as far as the Saxon plain in the north. Its central location in Germania beyond the Rhine was the reason it became the point d'appui of Boniface's mission work.