It appears that the majority of Old Norse literature from the 13th century is Icelandic as opposed to originating from other mainland nordic countries. The population of Iceland, as gleaned from the sagas (e.g., Laxdaela, Njal's, Egil's, Hrafnkel), was comprised mostly of farmers. With most people in Iceland being primarily concerned with farming and self-sustenance, why is it that this tiny island produced some of the most compelling and rich sources of world literature when the richer mainland countries from which the Icelandic people originated contributed far less?
Hi! FYI there was a similar question a couple of months ago; check out the discussion so far, and - since the thread is still open - join in with follow-up questions if you like
Perhaps tangentially, you may be interested in a couple of other posts about the production of the sagas
A correct answer would probably be that it is not fully understood, and IMO most theories are somewhat speculative.
Rather than writing more, a big difference is that Icelandic scholars wrote in Icelandic, rather than latin, which had become the main language of European scholars at the time.
Although a farming society, Iceland in the 12th-14th century time was a highly hierarchieal society, with a class of big landowners who were the political leaders AND also de facto ruled the matters of the church into the 14th century, which was different from the mainland, where the church was more independant. A lot of writing was done by priests or monks at monasteries or at big farms owned by leading chieftains.
At the time, the same language, Old West-Norse, was spoken in Iceland, Norway, Greenland, Faroe Isles and in the Norse settlements on the British Isles. There were regional dialects, but they easely shared a written language. The Old East Norse spoken in Denmark and Sweden was a seperate language, but nonetheless similar enough. Icelandic literature, written in the west norse language could therefore be read and understood in a linguistic area with a higher population than todays Iceland.
It is also useful to keep in mind that Norway in the 13th century was not a united political nation state, but rather many smaller area states who were legally independant from one another but who had the same king. Iceland probably had a population of 60-80.000 people at the time, making it bigger than most of the Norwegian area states.
There was golden age of writing starting in Norway at the same time as the writing of the Icelandic Sagas began. Egil´s saga, often considered the oldest saga, for example is considered inspired by the saga of Tristan and Isolde, which King Haakon the IV had had translated (If Snorri Sturluson is the author of Egil´s saga, he would have read/heard the translation in his latter trip to Norway).
The Black death epidemic of the 14th century bypassed Iceland but had a huge impact in Norway, mostly ending the writing era. A few generations later Norway had largely lost their old East Norse language but adopted the Danish written language instead. The other Nordic languages were also changing a lot more than Icelandic, which due to isolation was preserved.
Icelanders most likely were writing more than other norse at the time. But more importantly there was a continuation in Iceland which was lost in Norway, so a lot more was preserved.