Well, if we consider the decay rate of urban and rural areas and look at the materials used back in the golden age, as well as context given via lore. The golden age was a couple thousand years ago at minimum, then the dark age for several centuries, and now the city age. The iron lords disapeared roughly 400 years ago, and we know saladin would have been arround before that so at the verry least he would be around 400 years old(assuming he got res'd and immediatly joined the iron lords). BUT, in the trailer showing said battle roughly 400 years ago he still looks like an old grump, so either he looks that way cause guardians dont age, or we do age just very slowly, in which case hesbold as dirt.