A Description of the Northern Peoples, is a large work of 5 books, describing the history, technology and customs of Scandinavia, Samis, Iceland, the Baltic countries and Russia, but especially Sweden and Norway.

Magnus was the last Catholic archbishop of Sweden and by the time of publishing of the series in 1555, he had fled to Rome. It was widely popular at the time and translated into multiple languages. Ironically enough, it's first Swedish translation only came in 1909.

Each book is split in multiple chapters with each their woodcut, many of which you probably have seen before.

In terms of folklore, the books describe Nordic rituals, festivals and practices that by Magnus himself are often referred to as pagan. These include horseracing at Christmas, house helper spirits, dancing and singing about ancient pagan heroes and wearing masks.

Olaus Magnus' style of description is fascinatingly very reminiscient of later folkloric writing and he often compares practices he deem pagan to rituals in the ancient Rome.