In real life Nordic mythology, Thor and Odin are deities, similar to the Greek gods or the Roman gods.
In the MCU and other Marvel media, Thor, Loki, Odin, and other Asgardians are occasionally referred to as gods, but it is clear that they are just extraterrestrials who happen to be a lot stronger, have more abilities, and live a lot longer than the average human.
I always assumed that the in-universe explanation for why the Nordic people named their deities after them was that there was some contact between ancient Scandinavian civilizations and the Asgardians, but I can't find any references to how or when that contact actually happened. All the stories seem to start with Thor's present-day banishment to Midgard.
So what is the in-universe explanation of what the relationship is between Nordic culture and Asgard? Did Thor, Odin, etc...actually visit Scandinavia during ancient times?