chapotraphouse

This is difficult to answer precisely without my nice thick leatherbound copy of the series in front of me with its notes and appendices to quote from directly lol.

Trying to show weird through-lines and syncretism of recognizable cultural motifs is an important part of Herbert's world building. Here is a very good article published just before the first Villeneuve movie came out by a professor of Islamic Studies on this question but from the angle of the Islamic/Arabic influences on the text.

https://www.aljazeera.com/opinions/2020/10/11/paul-atreides-led-a-jihad-not-a-crusade-heres-why-that-matters

The trailer’s use of “crusade” obscures the fact that the series is full of vocabularies of Islam, drawn from Arabic, Persian, and Turkish. Words like “Mahdi”, “Shai-Hulud”, “noukker”, and “ya hya chouhada” are commonly used throughout the story. To quote Herbert himself, from an unpublished 1978 interview with Tim O’Reilly, he used this vocabulary, partly derived from “colloquial Arabic”, to signal to the reader that they are “not here and now, but that something of here and now has been carried to that faraway place and time”. Language, he remarks, “is mind-shaping as well as used by mind”, mediating our experience of place and time. And he uses the language of Dune to show how, 20,000 years in the future, when all religion and language has fundamentally changed, there are still threads of continuity with the Arabic and Islam of our world because they are inextricable from humanity’s past, present, and future.

You can replace Arabic and Islam in that final line with "Scandinavian" if you'd like, but the point being it's to make sure there's something in the setting that makes it feel both familiar and alien at the same time.