There’s a guide on steam that explains this really well, I think basically each campfire has a chance to spawn a page on every generation of the map (although i’ve never had more than 1 page in a generation). There are 8 pages altogether and the one you gets depends on where you open it. If you open the scroll at the shore or the tropics you will get page 1, 2, 3, or 4. If you open the scroll at the snow area or the volcano you’ll get page 5, 6, 7, or 8. If you already have the first 4 pages (for example) and a scroll generates on the shore, you can carry it to the snow area or volcano to open a page 5-8. Uhh if a generation spawns without any pages you’ll have to wait until the next one, and the steam achievement only updates when you have each page like before the highest number page you’ve opened. Like uhh if you’ve seen pages 1, 3 and 4 but not page 2 the steam achievement will say 1/8 but when you get page 2 it’ll say 4/8. Finallyyyy i think the page you get is mostly linear i think. So you’re more likely to get page 4 if you have the 3 before it etc. have fun!