I think a culture exists only when a certain nation state or a nationality declare themselves in a way independent. For examlpe Zionism, the great Jewish movement in the 30's and 40's was a type of nationalism, yet it carried a culture that was "different" as what we may think of Europe. I also don't think that culture should specifically have its own language. Culture is a natural phenomenon that gets produced with nationality and I don't believe that deafness should be considered a culture, since the only difference between us and the deaf population of the world is a small physical defect, not a whole different set of beliefs.
Thanks, Olzhas