Steve,
The Zvezda Strelets Infantry are made for the 1600-1660 'Eastern Wars' of the Thirty Years War period. They going excellently with Revell's Thirty Year Wars period figures -Swedes as well as the Imperials. At this time there were 'conflicting' sets of wars going on in the eastern European area. Sweden against Poland-Lithuania, Sweden against Tsardom of Russia [ for which the Strelets infantry were the major Muscovite forces], the Muscovites against Poland-Lithuania.....other conflicts were the Cossack uprisings and the Ottoman wars.
A lot of material is on the internet:

http://hem.passagen.se/ludde81/Historia/Krig/Nya_tidens_krig/130_Ingermanlandska_kriget.html

http://www.kismeta.com/diGrasse/PolishHorseArtillery.htm

http://www.conflicts.rem33.com/images/Poland/svenspolkriege%203.htm

http://www.gis.manewry.vdl.pl/viewtopic.php?t=593

http://www.jasinski.co.uk/wojna/index.htm

Take a look at these...and then you will have names and dates to SEARCH. Figures coming-up from several manufacturers...Zvezda, Orion bring Cossack force into your Muscovite army. Also, Luckey Toys Attila and Black Huns, and Italeri's Saracen and Mongels add can add some figures.
Kurt