Origin of the main theme from Tai Chi Shadow Boxing.

[Secret Executioner]

I mean that Spaghetti Western-like tune:

 

 

Well, it's a piece by Riz Ortolani from a 1967 Spaghetti Western with Lee Van Cleef called Day of Anger (original title: I Giorni dell'ira).

 

 

And it can be found on the OST of Quentin Tarantino's Django Unchained.  

[Lady Jin Szu-Yi]

Riz is  underrated as far as Italian composers from the 60s and 70s go. I liked this score... it was a more jazzy attempt at the spaghetti western style themes. 

[Morgoth Bauglir]

I watched Day of Anger about a month ago.  Good western.  Almost great.  The music is amazing.  I love how in the opening credits the song deteriorates at the end, because at the end of that great song we realize that our hero of the movie cleans up shit for a living.