Riders of Rohan

[Luddite]

I'd be thinking Late Roman as well.  What shape shields did the Rohirrim carry?

That's what i used, combined with riders from the Carthage range.

The Rohan had large round shields, mail shirts and haberks and 'charged fiercely with spears'.

[Fenton]

You could try having a look at this, it might give you some inspiration

http://www.toshachminiatures.com/Fantasy10.htm