You have to understand that the movie involves a lot of symbolism not found in Howard's stories (the wheel scene in the movies represents education, a seemingly circular activity that seems to go nowhere, yet develops the 'muscles' we need to survive in the world - while in school many people feel like they are going nowhere, yet when they leave the school, they realise they learned a few things); note that this turn at the wheel did not happen to Howard's Conan - he grew up in Cimmeria and was an able warrior by the time he fought at Venarium - the movie Conan never fought at Venarium - he grew up as a slave.
In addition to serving some symbolic needs, the presence of the Japanese-style Khitans also serves to explain why Conan-of-the-Movies fights in such a flashy Oriental style instead of as a western barbarian.
You would do well to divorce much of the movie from your mind. Although I enjoy the movie, it is not Howard's Conan at all.