It is. The written sources we have for norse mythology are 13th century, and those are compilations of earlier (lost) writings and oral traditions. There are w

It is. The written sources we have for norse mythology are 13th century, and those are compilations of earlier (lost) writings and oral traditions. There are written fragments from the 10th century referring to the norse gods. There are even 6th century writings referencing a germanic mythology with many similarities to the norse mythology.