I love her! Centurion was such a great little movie that managed to feel way bigger than its budget, filled with such a stacked cast of character actors. And 1602 was lots of fun. I was already in on the premise before I even knew NEIL fucking GAIMAN was writing it.
If you want all her Centurion history could have taken place, as I'm thinking the entire region is made up of warring cultures and city states, and a roman-esque one could have taken over her land for a spell.
Maybe her land was near Sylvania? As a woodswoman/cutwoman/witch I wonder if she might be privy to rumors and the like out of Sylvania (unless she's a native of there herself).