Languages

Do note that even thoguh languages may be in the same family, they can very well be utterly incomprehensible to each other. Case in point: Icelandic and the "mainland" scandinavian languages (Swedish, Norwegian and Danish).

Icelandic in it's modern form is much, much closer to ancient norse than the other three languages. While there are some similarities, icelandic is basically incomprehensible to a swede. It might be possible to decipher a word here and there, especially in written icelandic, but that's about it. Oh, and while Faroese is another language close to old norse, it is quite different to modern icelandic.

The differences between languages and how they arise is a long, complicated subject. Most modern linguists and historians reject the idea of "conquering tribes" imposing thier language on another population. Instead, migration, trade and other demographic factors are seen as much more important historically.

Of course, when nationalism arose in the early 1800's, the elites of several countries started looking for the cultural roots of the country, and if they couldn't find roots suitably ancient and impressive, they invented them, along with a glorious past. Thus, nationalist intellectuals in Norway wanted to emphasize the "norwegianness" of Norway, and deliberately created "nynorsk", a new dialect of norwegian that was supposedly an return to the old "true" norwegian, rid of harmful swedish and danish influences, in contrast to the danish-influenced "bokmål" spoken by the urban elites.

Other similar efforts were, for example, the fairy tales collected by the Brothers Grimm, the finnish heroic tale "Kalevala", and of course the british "Song of Ossian". While the brothers Grimm and the Kalevala where at least based on genuine folk stories, as opposed to the "Ossian", which was invented outright, they all served the same purpose: to influence contemporary events by inventing a suitable past and a suitable language.