Yemen is an unofficial name name given to 2 watches by Ariel Adams the guy that runs ablogtowatch.com the Yemen name is derived from its colors matching the Yeman flag. The watch is officially called a Speedmaster Date, it was produced for a year or 2 from about 2010 in that color scheme.
http://www.ablogtowatch.com/omega-speedmaster-date-yemen-watch/
There are a few different color variations of this watch out there made for a few years. Omega did not produce these in these colors for any specific reason other then it looks good.
Yours is the Omega caliber 1164 based on the Valjoux 7750. The Article linked above is wrong on what movements are in the watches.
https://omegaforums.net/threads/speedmasters-for-newbie.6794/ For more info and has correct movement information.
I have its brother which of the 2 is more normally referred to as the Yeman. Yours generally is not called the Yeman at least via google search and Omegas own embedded keywords.
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