Music by Ennio Morricone. Notice the play of major and minor harmonies, worthy of Schubert. Also notice that Morricone knows when to be silent. The harmonica music is a leitmotif, brimming with meaning, as the sequence makes clear. The clip ends, appropriately, in pure dissonance.
The Pacific Symphony Blog 
A classic! Very timely with the recent release of the “Dark Tower” by Stephen King whose character, Roland, is set in this time period as a gunslinger.
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