[NOTE: From this reply by GRRM at "Not a Blog".]
The Dothraki were actually fashioned as an amalgam of a number of steppe and plains cultures... Mongols and Huns, certainly, but also Alans, Sioux, Cheyenne, and various other Amerindian tribes... seasoned with a dash of pure fantasy. So any resemblance to Arabs or Turks is coincidental. Well, except to the extent that the Turks were also originally horsemen of the steppes, not unlike the Alans, Huns, and the rest.
There do exist many other cultures and civilizations in my world, to be sure. The peoples of Yi Ti have been mentioned, as have the Jogos Nhai. I am not sure to what extent those peoples will ever enter this present story, however... their lands are very far away.
(I also have peoples and tribes that are pure fantasy constructs, like the Qartheen and the brindled men of Sothoryos).
In general, though, while I do draw inspiration from history, I try to avoid direct one-for-one transplants, whether of individuals or of entire cultures. Just as it not correct to say that Robert was Henry VIII or Edward IV, it would not be correct to say that the Dothraki are Mongols.
[Note: Audio's a little hard to hear (ironically), so raising the volume may be useful.]
[Note: Martin appears most prominently about 7 minutes in, discussing the works of Jack Vance, and then at the 45:50 mark answering a few questions.]
[John Hodgman, writer, actor, and comedian, fills in for Jesse Thorn for this interview. Hodgman was invited to write the profile for GRRM for the TIME 100, and has previously spoken about his appreciation of the series and Martin's efforts, as well as referenced these things on The Daily Show.]
[NOTE: This is from private correspondence without the usual header information we use to verify. However, a screenshot of the message can be seen here, with the name of the respondee redacted.]
Who would win in a fight, Barristan Selmy or Arthur Dayne (in their best days)?
Dayne... if he was armed with Dawn.
If both men had equivalent weaponry, it might be a toss-up.
George said that artists have trouble with Dragonstone because they draw it like a normal castle with dragon statues adorning the walls. It is the only castle in Westeros built by the Valyrians and they had a powerful magic which could liquify stone and shape it how they want. (Inspiration for Stone-made-soft in the Long Price perhaps?) So Dragonstone is literally shaped as a dragon with doorways opening in their mouths.