Was wondering if anyone can I'd these uniforms by regiment or even branch, weapons, uniform type etc. They were taken in China c. 1912 and shows members of the Russian Legation Guard in front of their Legation and with a US Marine Guard. Thank you!

They're probably from one of the many Siberian Regiments, Siberian Rifle Regiments and Artillery Regiments and Siberia Cossacks were exclusively in the Boxer Rebellion. Cossacks from Asiatic Russia  as well, the  Transbaikal Cossack Host and Amur Cossack Host, 

 

A List of them here.

 

http://marksrussianmilitaryhistory.info/BoxerReb.htm

Thank you so much for the info!!!