A couple of things I've noted...
The character creation section specifies Moon Shamans as male and Sun Shamans as female, but this isn't reflected in the Black Pavilion section. Also, the Black Pavilion section states that he division into Black/Moon and White/Sun shamans is unique to Black Pavilion, while the character creation section implies that this division applies to all Steppes Shamans. There are also subtle differences in tone between the two sections. For example:
Black PavilionAlone among the Urgar the Black Shamans are regarded as more powerful than their White (and Yellow) counterparts, and their rule is absolute in the Black Pavilion.Character Creation...it is the Moon Shamans who can be found most often among the populace, offering spiritual guidance, practical advice and protection from both supernatural and mundane threats [...] while both paths are respected and honoured among the nomads, it is the Sun Shamans that are fearedI would be tempted to structure it something like this:
1. Niccolo's writings
2. The Steppes Shamans (incorporating/merging the general material on Shamans from the Black Pavilion section with the Introduction from the character creation section, and ironing out the inconsistencies)
3. The Gunguska (or could have this section before the Shamans)
3. Black Pavilion (focusing on the incorporation of Sorcerors and Mystics into their ranks, and also introducing the Yellow Shamans)
4. Codex Cryptozoologica II
5. Along the Way
6. Shaman character creation [if not included in #2 above, but I can see why you might want to put this at the end rather than interrupt the flow of the background sections. Alternatively, you could put it between #3 and #4]
Stop me if I'm being a pain..!