Greetings!
My own world of Thandor has always been deeply historical. Thandor is a fantasy world, but a fantastic world that has many layers of real-word History that inspires it throughout the milieu. I have carefully developed regions featuring Ancient Roman and Greek cultures, as well as the Celts, the Germanic barbarians, and the Norse. I also have huge regions that feature barbarian Slavic culture, Baltic barbarians, Finnish barbarians, and synthesis cultures blending primitive Uralic and Asian tribal peoples. There are also ancient Iberian influences, as well as Etruscan, Phoenician, and Carthaginian influences and cultures. In other regions of Thandor, I have over a dozen cultures inspired by the Mali, the Numidians, the Berbers, the Swahili, Maasai, Kenya, the Zulu, and the kingdoms of Axum, Ethiopia, and Nubia, as well as the Bedouin and Arabic cultures. Then there are the Parthians, the Persians, the Hittites and Egyptians, as well as the cultures and peoples of Central Asia. I have very detailed regions embracing a variety of Steppe cultures and kingdoms, being inspired by the Huns, the Magyars, the Scythians, Avars, the Pechenegs, Tatars, the Kazakhs, the Soggdians, the Kushans, the Kwarazaam, and the Mongols.
I couldn't stop with that, either. I then developed regions embracing ancient India, over a dozen cultures, peoples and kingdoms there, as well as ancient China, Korea, Japan, South-East Asia, the Tibetan Empire, the peoples and kingdoms of Nepal, Burma, Malaysia, Indonesia, Thailand, and Vietnam. There are of course many fantastic elements and weird races and peoples too, with a variety of cultures being formed that are essentially hybrid cultures--blending two or more different cultures and peoples together. While not always highlighted in popular history in our own real world, these kinds of hybrid cultures and mixed societies and peoples have been going on forever, from the beginnings of history. I have fun tossing fantasy races and cultures into a blender with history-inspired cultures, peoples and religions, and create some new things that are always pretty interesting and cool, and at least entertaining.
I have different religions in my world of Thandor, both Polytheistic and Monotheistic, but also various varieties of Barbarian Paganism, Dualism, Monism, and more. Lots of crazy different religions, many of which do not get along and play well together. Just like throughout history, people prefer their own religion and their own culture and race, so others that are different in whatever ways are routinely discriminated against--and often persecuted and oppressed. In some areas, race isn't a big issue, but culture and religion very much are. Similarly, in other regions, race is seen as the most prominent thing. And every dimension embraced with such variables. It creates a richer and more dynamic campaign milieu where all of these considerations and aspects are important and meaningful, and have accordingly their own benefits and drawbacks alike, depending on the region, culture, or people.
Genuinely cosmopolitan, open-minded and accepting societies that place relatively low values or emphasis on race, religion, or culture are quite rare, and tend to stand out like islands in a sea of an entirely different reality. I'm often inspired by trends and attitudes of different cultures in India, the Song Empire of China, or the culture of Norman Sicily, or the culture of the Kazakhs ruling the silk-road city of Samarkand. Very inspiring and fascinating on so many levels--and yet, nothing like Seattle 2020.
I use real world History to inspire much of the world of Thandor, and have done so for decades. Adding in fantastic races and cultures, religions and different elements makes it all very fun, and quite wild.
Semper Fidelis,
SHARK