No

Two very good guesses though!

Spartans?

No.

You do not need to specify a time period. The name of the group will sorta go hand in hand with the time period... sorta. Just name the group :)
No

French

Okay, then just asking: is this group from before Christ?

Off the top of my head, I don't know how long they date back. But, I'm thinking of a time after Christ which they would be most known for.

Does the civilization still exist in a similar form? (i.e; not ancient romans/ spartans)

In large part, the group of people still associate themselves with the name they used to use.

Nazis?

Is the group directly related to a country?

Native Americans?

No

I don't necessarily know how to answer your question. To me, at least, I don't think of a specific country when I hear their name... but, most of them do reside in one current country I believe.
Nope.

Vikings?

No

U.S. revolutionaries?

Did they fight modern wars, with tanks airplanes etc.?