During republican times, the cavalry were formed from the rich or the nobles. There were never too many of them and the Romans seemed to like fighting on foot better. As Roman grew and her army expanded, her cavalry were always auxilliaries, hired from allies or from subjugated foes.
There are 12 mounted figures per box, 4 poses of riders and 2 of horses. The cavalry at this time wore a variety of armor so you see muscle cuirasses and mail armor as well as a variety of helmets. Figure #2 can also be used as a commanding officer for the Roman foot figures. Here are the riders.
