Yes he has taken a bit of Morocco, a bit of Spain, and a bit of Wales (actually not sure what is Welsh about Dorne??) and he used that to create the flavor of Dorne. It is not that interesting.
I suppose it is much easier to take existing real world cultures than to make one up from scratch. With a real world culture you take the amalgamation of the art, architecture, fashion, food, language, etc. of millions of very gifted and creative individuals built up over 1,000s of years. To create something like that by yourself for a fantasy novel would be no easy task. So I understand why fantasy writers do it.
I think the closest someone has come to successfully creating unique, original, and believable fantasy cultures is Tolkien. Though he definitely was influenced by real world cultures (Hobbits are English, Gondor is Byzantium, Numenor is Atlantis, Harad are Moorish, etc.) he did at least give them some unique and original cultural traits. The way he created beautiful languages and scripts really gave Middle Earth a lot of depth and a feel that it could be real. I love all the place names written in his invented languages (Dol Goldur, Cirith Ungol, Minas Tirith, Dol Amroth, etc. etc.). The place names are far more interesting than the place names in Game of Thrones: Lemonwood, the North, Winterfell, Kingswood, Castle Black, etc. kind of boring and uncreative imo.
There is more than just that. There is monotheistic god, archangels with one in rebellion, lower angels, a perfect people in the form of the Eldar (Adam and Eve type perfection), a chosen people (Men of the West), a lost people (Men of the West which follow the Enemy) and people led by a false religion via Melkor and Sauron (Men of the South and East). This is very similar to Judaism in how it breaks down bloodline between Abe and Cain along with the conflict between these family lines. The people of the south and east are lesser men compared to those from the west. They do not live as long, they are not as physically fit, they are smaller, weaker, less intelligent and easy to compel. This does reflect the common view the Western Civilization as superior to the Hordes of Asia and Africa.
Keep in mind the names of a lot of places are in another language, Sindarin. Minas Tirith in English would be Tower of the Watch or Tower of the Guard. Just as Paris really means Midwater-Dwelling in English. In GoT English is the common language thus there is less romanticizing over names of places while the common language in Tolkien develops far later in history. The chain of develop starts with the Three Houses of Men as a Mannish language, although I assume Eldar loanwords were introduced due to the background stories. It mirrors the development of English as a Germanic in comparison to Eldar "Latin" branch languages. Just as with Latin an Empire was established under "one language group" only to seceded by another language group. Sindarin would have been the language of the nobility and educated as Eldar knowledge would have been communicated in Sindarin.
Topic: Game of Thrones