Try "Warriors of the Steppe: A Military History of Central Asia, 500 B.C. to A.D. 1700".
Amazon Link: http://www.amazon.com/gp/product/0306810654/qid=1135150831/sr=2-1/ref=pd_bbs_b_2_1/103-2469063-9097466?s=books&v=glance&n=283155
Right up my alley. Great book. I read it last year on a freeper recommendation. It may have been yours.