English: Map showing the approximate extent of the Old Frankish language during the 6-7th century.

Legend:

• 1: Old Frankish language area (ancestral to Old Low Franconian and partially to Old High German)
• 2. Northsea Germanic dialects (ancestral to Old English, Old Frisian, Old Saxon)
• 3. Elbe Germanic dialects (partially ancestral to Old High German)
• Red line: the Somme-Aisne-line, north of which Germanic toponymns dominate.
• Yellow line: approximative extent of the High German consonant shift during the Early Medieval Period. (note: its position is not identical to that of the later Benratherline, as the current westernmost position of this isogloss is due to 12th and 13th century developments)

Based on:

• Kerkhof, P.A. [Peter Alexander]: Language, Law and Loanwords in Early Medieval Gaul: Language Contact and Studies in Gallo-Romance phonology, Doctoral Thesis, Leiden, 2018, pp. 24 [it's either p. or other pages are missing]. [1]
• Ryckeboer, H.: Het Nederlands in Noord-Frankrijk: Sociolinguïstische, dialectologische en contactlinguïstische aspecten, Gent, 1997, pp. 183-4. [2]
• Cowan, H.K.J: Oudoostnederfrankisch of oostelijk Oudnederlands? [Old East Low Franconian/Frankish or eastern Old Netherlandic/Dutch?], in: Tijdschrift voor Nederlandse Taal- en Letterkunde, jaargang 71. E.J. Brill, Leiden, 1953, pp. 161-182. [3]