I found that I had completed most of the tombs, but I was missing a lot of sigils. So I checked to see where each sigil is (which tomb), then went back to those that I'd already done and (using internet tips) searched again and found the sigils. I just didn't notice them - they're often in a locked room that can be easily not noticed. That worked for egypt and china, haven't tried france yet. The only trouble I had was in the copper quarry - (which doesn't need an adventure I think) had to meditate and teleport to get it, along with having the right key stone. Hope this helps - if you need help working out each sigil, use the guide pages to check which tombs they're in, then look up on google where to find them within the tomb - I found information on all the ones I'd missed.
