So my thought is, how do you approach using monsters that draw from a different culture than the ? i.e. Indian rakshasas in a European-based setting, or Egyptian mummies in a Chinese-based setting, or European vampires in an Incan-based setting, etc.
My current campaign is set in a fantasy world inspired by Andean/Incan history, which was originally created by my son. However, the fantasy features are drawn from standard D&D, which has a mix of mostly European with some mix of the Near East, India, and East Asia. I find that it's a difficult learning curve if the players need to deal with unfamiliar magic, monsters, and races as well as unfamiliar culture. So the standard elements of D&D makes it easier for players to jump into.
Still, sometimes stuff can seem out of place. I'm finding that my approach is to find a local hook - something in the local culture that the monsters connect to.
So, for example, the big monster in the last adventure was vampire spawn. I connected this to a night-worshipping cult based on an Andean creation myth that the Sun threw ashes in the face of the Moon to dim her shine. Since this reflects poorly on the Sun god Inti, who is the patron of the Empire, the myth became a basis of a cult that opposes the Empire.
Also, when dealing with dragonborn society and ancient dragonborn wraiths, I tied in the Amaru Aranway myth about two dragon gods that were fighting, and were turned into stone that became local mountain chains. In the campaign, these two represented the metallic and chromatic dragons (the equivalent of Bahamut and Tiamat).
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I was thinking about this process, and how it might apply for other mixes of settings. Do other people only have mummies if the PCs travel to an Egypt-like part of the setting? Or do you just drop a mummy into the local area without having any Egypt-like connection? Or do you find something more local-seeming that might connect to mummies?