They lived between the Meuse (Dutch Maas, Latin Mosa) and Rur rivers in Roman imperial times.
[1] The Sunuci dwelled in the western part of the modern Rhineland region, around the towns of Eschweiler, Heimbach, or Kornelimünster.
[5] The origins of the tribe are unknown, but it is likely that, like their eastern neighbours the Ubii, their ancestry included Germanic immigrants from the east of the Rhine who had been arriving for generations.
Germania Inferior was on the west of the Rhine and had been described by Julius Caesar, at the time of Roman conquest of the area, as part of Belgic Gaul.
Some specific tribes who entered the empire later, such as the Ubii who lived between the Rur and the Rhine, are generally understood to be speakers of Germanic languages, and records exist concerning their immigration and settlement.
On the other hand, there have been suggestions that they might represent the descendants, at least partly, of the Segni, one of the Germani tribes described by Caesar as having been in this region since at least the 2nd century BCE when the Cimbri moved through the area.
There is evidence from tablets found in the Rivelin Valley south of Stannington that retiring Roman auxiliaries of the Sunuci tribe stationed in Britain were made grants of citizenship and land or money in the modern day city of Sheffield, with some speculation that a Roman villa complex at Whirlow Hall Farm was part of such a land grant.