structural:summarization
Old Norse

In the 8th century, the common Germanic language of Scandinavia, Proto-Norse, evolved into Old Norse. This language underwent more changes that did not spread to all of Scandinavia, which resulted in the appearance of two similar dialects: Old West Norse (Norway, the Faroe Islands and Iceland) and Old East Norse (Denmark and Sweden). The dialects of Old East Norse spoken in Sweden are called Runic Swedish, while the dialects of Denmark are referred to as Runic Danish. The dialects are described as "runic" because the main body of text appears in the runic alphabet. Unlike Proto-Norse, which was written with the Elder Futhark alphabet, Old Norse was written with the Younger Futhark alphabet, which had only 16 letters. Because the number of runes was limited, some runes were used for a range of phonemes, such as the rune for the vowel u, which was also used for the vowels o, ø and y, and the rune for i, also used for e.

From 1200 onwards, the dialects in Denmark began to diverge from those of Sweden. The innovations spread unevenly from Denmark, creating a series of minor dialectal boundaries, or isoglosses, ranging from Zealand in the south to Norrland, Österbotten and northwestern Finland in the north.

An early change that separated Runic Danish from the other dialects of Old East Norse was the change of the diphthong æi to the monophthong é, as in stæinn to sténn "stone". This is reflected in runic inscriptions where the older read stain and the later stin. There was also a change of au as in dauðr into a long open ø as in døðr "dead". This change is shown in runic inscriptions as a change from tauþr into tuþr. Moreover, the øy diphthong changed into a long, close ø, as in the Old Norse word for "island". By the end of the period, these innovations had affected most of the Runic Swedish-speaking area as well, with the exception of the dialects spoken north and east of Mälardalen where the diphthongs still exist in remote areas.