Forward:
With fantasy, you can pretty much make up the entire thing. (Why are so many set in Medieval times?) Not true with Sci-Fi. There has to be a believable explanation for the tech, physics, abilities, etc. This means there are likely to be references to trace back where ideas came from. Especially true when another recognizable culture is involved, like the Hopi or the Chinese in the case of the early books.
Of course all writing is really on a scale from known to pure imagination. Sci-Fi tries to bridge the gap between documentary and pure fantasy/imaginary. Documentaries are intended to be an accurate recording of actual events. Nearly impossible to keep all bias out, but the author tries to be accurate and fair. Sci-Fi tries to predict a believable future based on present knowledge and theories (true or not only time will tell)
This series of books starts out in a recognizable current time, even if not our time line, and then progresses from there given a set of circumstances and events that have not actually happened (yet), but potentially could happen. Maybe. Guardians is not near Sci-Fi and more in the middle between Sci-Fi and Fantasy. A resonable explanation is given. still dependent on a projected understanding of physical (and psiotic) principals. See also Forward/Glossary
The early books deal with 'what the hell is happening' as might be expected for anyone new to TK, 'thn and all the rest. Later books get more into 'what the hell is all this for or about' or THE QUESTION as it is referred too. ALL beings need to answer this of course, but in the case of our participants they are attempting to answer this for all of creation. I will stop here rather than give too much away. Enjoy!
References:
Hopi Tribe official website Check out their newsletter
Library of Congress map of tribes in USA before the European invasion
Library of Congress map of reservations in USA after the 90% loss in population from diseases and war with Europeans
On-line Hopi Dictionary easiest way to look up words
The Dictionary that I used (archive version of the hard copy I used) THE source for understanding the language/grammar/pronuciation.Search results for 'The Hopi Prophecy' Traditionalists vs Progressives and the end of the world and the beginning of the 5th age.
Google Map of the Reservation looks like Mars. Very little rainfall. Primary crops are the 'Three Sisters' (native corn, beans, squash) and sheep.
A nod should also be made to the daily reports in blogs like PHYS.ORG where amazing finds are reported that could lead to amazing tech and new understandings on how the universe works?