The earliest stories of German and Scandinavian literature probably come from even earlier Indo-European stories. Some of these stories seem to be related to stories told by other Indo-European people like the Persians or the Greeks. Because nobody in northern Europe used writing, we don’t know much about these early stories.
In the Middle Ages, men and women in the Holy Roman Empire (modern Germany and Austria) became Christians, and some of the monks and nuns learned to read and write in order to be able to read the Bible. Soon they began to also write their own stories down. About 830 AD, somebody wrote down the Hildebrandsleid, the story of King Hildebrand, and around 1000 AD somebody wrote down the story of Beowulf. Another famous story is the Niebelungenleid, from around 1200 AD. Around this time, people also wrote down many other stories, like the Orkneyinga saga. These stories have the same kind of plot about warriors fighting each other.