[There's a distinct curl to his lip as he responds.]

Caesar's Legion. A slaver army, made up mostly of the remnants of old tribes Caesar conquered. They raid towns and enslave those they see as useful, then kill the rest. If you're lucky, your death is quick. Men become soldiers. Women... are treated as less than slaves. They like to crucify their enemies and disobedient slaves... make an example of them.

[So yeah, they're fucking psychopaths too. Boone scowls to himself, and apparently misses the last part of what Roy is saying.]