| This similarity was reinforced in the late Middle Ages by the Ingvaeonic sound shift, which affected Frisian and English, but the other West Germanic varieties hardly at all. |
| Changes in this period affected the Ingvaeonic languages, but not the more southerly Central and Upper German languages. |
| There are also various differences in their phonological evolutions, Old Saxon being considered as an Ingvaeonic language whereas Old Dutch is an Istvaeonic language. |
| The dialect of the Germanic people who remained in Scandinavia is not generally called Ingvaeonic, but is classified as North Germanic, which developed into Old Norse. |
| The related Low German has developed differently since Old Saxon times and has lost many Ingvaeonic characteristics. |
| Some classify the northern dialects of Low German together with English and Frisian as the North Sea Germanic or Ingvaeonic languages. |
