Fantasy Counterpart Culture
Fantasy Counterpart Culture is a /tg/-relevant term shamelessly stolen from our frenemies over at TVTropes. In a nutshell, worldbuilding is hard, so, what's one way to make it easier? Why, it's to take real life cultures and slap them into your game!
There's... not much more of a way to describe it. The phenomena of Fantasy Counterpart Cultures is wide-spread, and has been going on at least as long as /tg/ has existed - Dungeons & Dragons (and, by inheritance, Pathfinder) is infamous for it. It's an easy way to get a solid base, and whilst it can be executed in a lazy fashion - the Knorrmen of Jakandor are such a blatant mish-mash of Viking and Native American it makes one roll the eyes - it's not inherently bad.
Fantasy Counterpart Culture is particularly likely to be used in a lazy fashion when dealing with "exotic" (to the author) cultures. It's a recurring issue for Oriental Adventures, and Maztica has been blasted for how lazily it does "South American Fantasy" by literally just putting South America in the Forgotten Realms.
The two settings of D&D that rely most on Fantasy Counterpart Cultures are Mystara and Golarion.