[4] Pliny the Elder further specified its meaning by claiming that the Istævones lived near the Rhine.

[5] Maurer used Pliny to refer to the dialects spoken by the Franks and Chatti around the northwestern banks of the Rhine, which were presumed to be descendants of the earlier Istvaeones.

[6] The Weser is a river in Germany, east of and parallel to the Rhine.

The terms Rhine–Weser or Weser–Rhine, therefore, both describe the area between the two rivers as a meaningful cultural-linguistic region.

Maurer asserted that the cladistic tree model, ubiquitously used in 19th and early 20th century linguistics, was too inaccurate to describe the relation between the modern Germanic languages, especially those belonging to its Western branch.