[Thieves' World] Mages lifespan

[Dracain]

I've been reading the anthologies lately, and I keep seeing magicians referred to as extremely old, being able to extend their lives (and the lives of others) for a very long time. Now, I haven't read all the books in the original series, but I wanted to ask if there was anything on a wizards lifespan, or how they can extend their lifespan in the RPG. Because it seems to be a common ability among wizards in this setting, and it has no representation in the rulebook, so I just figured I would ask if someone had any information on that. Thanks for any answers and sorry if my question seems a little muddled.

[Nikodemos]

Life to you, Dracain. And everlasting glory.

Just had a look through the RPG, books and there's nothing. However having read the majority of the Rankan, era novels; most magic users make pacts with other worldly powers. These pacts have two benefits they increase the users power and enhance their lifespan, dependent on how powerful the mage is they can pretty much live for centuries.