So then, using the same logic, and since France did not come into existence until 843, Charles Martel is not French (as the French claim) because he died roughly a hundred years or so before France became a nation.
Martel was born in what is now Belgium.
"So then, using the same logic, and since France did not come into existence until 843, Charles Martel is not French"
You meant 1843, of course. I agree, Martel was not French.
And Roger Staubach was not a Dallas Cowboy when he played for Navy, even though the Cowboys did exist at the time.