Yeah, I know, as old as he needs to be for the storyline.
Still, I wanted to work that out from the Savage Worlds Rules As Written. That would give me a minimum age, and thus allow me to describe the liche better in play (“You see a long-dead corpse in the regalia of a court wizard of the Empire of the Wolf. As you creep closer, its red eyes open, and the apparition speaks…”)
See, I started with the impression that liches would have to be hundreds, maybe thousands of years old. I was wrong.
If you look at the SW liche, and assume it started off with the same stats as a Novice PC, it needs 61 advances to get to the statblock in the rulebook. My assumption from earlier posts is that it takes about 18 months for NPCs to earn an advance. Assuming he started racking up advances about age 18, then, the stock liche is about 110 years old. He could be older, and have used more advances to bump up things not listed in the statblock – Connections, for example, or other skills.
So, the liche could be dressed in the fashions of your great-grandfather’s time, or any earlier period. Or a later one, if he wanted, I suppose.