
Aref al-Arzani |
Male Human (Keleshite)

Seems pretty straight forward to me. You either joined the caravan in Sandpoint or somewhere along the road. Joining in the Crown of the World seems unlikely considering the fact that it is a remarkably inhospitable place.
In my current version of Aref's backstory, I'd been considering the previous characters from the last attempt at this campaign as being canon members of the party who either parted ways with us along the road or perished and were buried on it (*sniff* poor Enod Helmcleaver, we shall miss you). Your presence can, of course, be retconned into the history pretty much anywhere along the line since there is pretty regular trade between Tian Xia and Avistan and those trade routes were what we were travelling.