Where is Quantez?

Somewhere in the fictional wild west, and in the fictional southwest since there are Apaches.

But if it happened in the real west it would have to be in eastern New Mexico or western Texas.

I just saw Quantez on Starz Encore Westerns 04-28-2019. The gang is holed up in the deserted town of Quantez and hoping to reach Mexico.

And Gentry/Coventry tells Heller that he knows the water holes in the desert between Quantez and the Rio Grande. Apparently a lot of desert has to be crossed to reach the Rio Grande because he says that five horses couldn't carry enough water for themselves and their riders to get all the way to the Rio Grande without using the waterholes.

But of course that is no help in locating Quantez because the Rio Grande is the border between the USA and Mexico all the way from the Pacific Ocean to the Gulf of Mexico, right?

No, the Rio Grande flows through New Mexico from north to south and then turns in a generally southeast direction at the point where New Mexico, Texas, and Mexico meet, and then forms the border between Texas in the USA and Mexico. The border between California, Arizona, and western New Mexico in the USA and Baja California, Sonora, and Chihuahua in Mexico is dry land - very dry in places - as is seen in the opening of A Distant Trumpet (1964) when the Apaches cross a patch of desert and General Quaint halts his pursuit because it is the border.

So it is possible that Quantez in somewhere in Texas far downstream of New Mexico, somewhere near the locations of Bandolero! (1968). Or it could be in southeastern New Mexico or far western Texas, near the triple point of New Mexico, Texas, and Mexico, near the locations of Duel in the Sun (1946) and The War Wagon (1967), and near where Major Dundee (1965) crossed into and back out of Mexico.

In real history, the Mimbreno Apaches of Victorio lived near the borders of Arizona and New Mexico, west of the Rio Grande, though they raided far and wide. Since Delgaditio told Gato that Victorio was moving whites off their land before beginning war with the whites, Quantez should have been in Mimbreno territory. So apparently in the fictional universe of Quantez the Apaches led by Victorio lived a few hundred miles east of their real homeland.

Or maybe the Rio Grande, also called Rio Bravo in Spanish, has a fictional branch or tributary that comes from the west and forms the border between eastern Arizona & western New Mexico in the north and Mexico in the south. As I remember, in Fort Apache (1948) the Rio Bravo had to be crossed to reach Mexico, so either there are two Fort Apaches in the movie universe, one in eastern New Mexico or Texas and one in Arizona like the real fort, or else there is a fictional west branch of the Rio Bravo/Rio Grande that forms part of the southern border of Arizona and western new Mexico in some movies, and thus Quantez could be in western New Mexico or even in Arizona.

you never can tell with movie geography.