While reading the "Song of Ice and Fire", I noticed very fast, that George R. R. Martin did get a lot of inspiration from real live cultures and history. The world builing is excellent. One can even clearly recognize some real peoples/countries/groups of countries in some of the peoples and countries in the books. A few times even individual people.
Let’s start with Westeros. I think it is pretty save to assume that Westeros is inspired by Europe (even the word "west" is in the name). The society is largely a medieval european one. Also the fauna and flora is a pleistocene european one (wild boar, wolly mammoth, red deer,…), spiced up a little with some new world (dire wolves, pumpkins,…), a few asian (peacocks, tigers(?),…) and even fewer australian (black swan,…) organisms. Additionally a few creatures from european mythology (dragons, giants,…) and some invented (white wanderer, weirwood trees,…) were added.
The story seems to be largely inspired by the War of the Roses in Britain.
The 7 Kingdoms: Dorne = Iberia (Spain, Portugal and Andorra) The Reach = France The Westerlands = UK The Stormlands = Italy The Vale = Romania and Hungary The Iron Islands = Ireland The North = Germany (I have to mention that with the Stormlands and the Iron Islands I am not 100 % sure)
Other important places or places within those kingdoms: Beyond the Wall = Scandinavia (Norway, Sweden, Finland and Denmark) The Wall = The Teutonic Order (and maybe some other knights orders) Skagos = Iceland Oldtown = Vatican The Riverlands = Balkans
Islands Summer Islands = southern India and Sri Lanka
Essos Free Cities = Greece Dothraki = Huns or Mongols Valyria = Rome/Roman Empire Slaver’s Bay = Ancient Egypt
The war of the roses is the most frequently cited inspiration but I think there is also some Roman history to be found in Westeros.
The Targyrians are pretty obviously based on the Ptolemy dynasty. They are a foreign dynasty that conquered the nation from the original inhabitants, they have an exotic flair to them, have a long history of incest and their most famous member is a powerful queen.
The Lanisters have a striking similarity with the Roman Severan dynasty. Both the Lanisters and the Severans had two boy rulers. One boy was insane and the other boy was a weak mommiesboy. Both boy rulers were under the control of their powerful grandparents.
Stannis is also stated by Martin to be based on Tiberius. Considering they are both dour, unappreciated and stuck on their little island its quite an accurate comparison.
The 7 Kingdoms: The holy roman empire in a way.
Dorne = Spain
The Reach = Rhine Lands
The Westerlands = Wessex (At the time of Alfred the Great)
The Stormlands = Scotland
The Vale = The Alps
The Iron Islands = Nordlands
The North = Poland/ The Rus
Beyond the Wall = Finland/ Siberian wastes
The Wall = Hadrian wall border troops
Oldtown = Rome
The Riverlands =Central england
Xu-something = China
Free Cities = Athens
Dothraki = Huns
Valyria = Ancient Babylonian maybe?
Slaver’s Bay = Eastern roman empire