No country? Why not? Which country???

Tommy Lee Jones seemed a bit old and tired to me. Maybe he was getting too old for this shit...

It's the first line of the W.B Yeats poem, Sailing to Byzantium.

That is no country for old men. The young
In one another's arms, birds in the trees,
—Those dying generations—at their song,
The salmon-falls, the mackerel-crowded seas,
Fish, flesh, or fowl, commend all summer long
Whatever is begotten, born, and dies.
Caught in that sensual music all neglect
Monuments of unageing intellect.

An aged man is but a paltry thing,
A tattered coat upon a stick, unless
Soul clap its hands and sing, and louder sing
For every tatter in its mortal dress,
Nor is there singing school but studying
Monuments of its own magnificence;
And therefore I have sailed the seas and come
To the holy city of Byzantium.

O sages standing in God's holy fire
As in the gold mosaic of a wall,
Come from the holy fire, perne in a gyre,
And be the singing-masters of my soul.
Consume my heart away; sick with desire
And fastened to a dying animal
It knows not what it is; and gather me
Into the artifice of eternity.

Once out of nature I shall never take
My bodily form from any natural thing,
But such a form as Grecian goldsmiths make
Of hammered gold and gold enamelling
To keep a drowsy Emperor awake;
Or set upon a golden bough to sing
To lords and ladies of Byzantium
Of what is past, or passing, or to come.

"Country" is a word used in the general sense imo.

Texas is a very large state. It also involves Mexico and the border. Some Texans think that Texas is akin to a whole country. Like "The Big Country".

https://www.imdb.com/title/tt0051411/

Anton Chigurh's nationality is never stated and is left deliberately vague too.

Surviving the events depicted would favor the young, decisive, and quick-thinking. Not to dismiss the wisdom of "old men" though.

It is vague and open to interpretation.

I took it more loosely to mean that times change and the older generation can't meet or understand the newer challenges of the times they now inhabit.

So in my reading "country" would be the equivalence of "world," in effect, but still would still reference the times and setting where one find themselves.

I think in the opening monologue he says something like "I'll be a part of this world" at the end.

Not saying this is the proper interpretation mind you, just that it's how I understood it without really thinking about it.