> I was babbling on here about the Cossacks a while ago, and the thought
> occurs to me: Does anyone know of any other instances in history in
> which a group that was artifically created by a state (in this case, for
> military purposes) over time developed into a group that considers
> itself to be an separate ethnicity? I would think it's a pretty singular
> development.
I think what you have here essentially is an ethnicity created through colonization. What makes it look odd compared to its European contemporaries is what make Russia odd in general: that its empire was a contiguous land empire where other countries were of necessity colonizing overseas. So the only reasonable way to compare Russia to other European countries during the same period would be to look for other ethnicities created through long-distance relocation. Afrikaners and Americo-Liberians come to mind. I'm sure there are many others. Norsemen creating Normans also springs to mind. The myriad local mixed races of Latin America, ditto.
As for ethnicities specifically created through relocation for purpose of defending a distant frontier, I'm sure if we combed through the long annals of empire history we'd find lots of cases now forgotten but who in their time had the same significance as the Cossacks. The Islamic empire seems like it should be particularly full of good examples; many of its greatest cities started off as garrison towns. Similarly with the Turkish empire, the Persian empire, the Mogul empire, etc.
These other frontier guardians may not have claimed a separate ethnicity in the same way, but that's only because in their time there was no money in it. But their customs and political identity seem in many cases to have become pretty clearly differentiated from that of their homeland to an even greater extent than the Cossacks have from Russia.
Weber in fact went so far as to say that all ethnicity (to the extent that it has any real substratum beyond its imaginary aspects) has its origins in political events, usually either through forced emmigration, forced immigration (i.e. conquest) or political division. In many ways, the definition of an ethnicity is that it's a piece of a nation that got separated and surrounded by another one.
Michael