Wikipedia
The Sicambri, also known as the Sugambri or Sicambrians, were a Germanic people who during Roman times lived on the right bank of the Rhine river, in what is now Germany, near the border with the Netherlands. They were first reported by Julius Caesar.
Whether or not the Sicambri spoke a Germanic or Celtic language, or something else, is not certain, because they lived in the so-called Nordwestblock zone where these two language families came into contact and were both influential.
By the 3rd century the region, in which they and their neighbours had lived, had become part of the territory of the Franks, which was a new name that possibly represented a new alliance of older tribes, possibly including the Sicambri. Many Sicambri had however been moved into the Roman empire by this time.