How about doing some Persian armoured cavalry for the late 14th and 15th centuries? The armour was of similar style from Egypt right through to the Delhi Sultanate.
If the figures were split like those from the TB range you could initially do 3 different bodies (sword and shield, bow firing with shield and lance and shield) all with scale armour and eastern helments. Ref Armies of the middle ages vol 2 figures 26-31. Then 3 different horses (laminar/scale armour, fabric and no armour). Ref Armies of the middle ages vol 2 figures 156-159. I assume its possible to get all that in one pack of 15? The same horses could then be used for another set of different bodies to expand the flexibility further (possibly with only 1 more pack of 15).