This is one of those speculative books that explores the question of whether there was any advanced civilizations prior to those of which we know. The book explores the concept of lost civilizations and looks for evidence supporting their existence than looking at the civilisation that we already know. Unfortunately, with ancient civilizations, there are only two ways of trying to understand them: archaeology and literature. Further, you need to look at both together to come to a good understanding (if that is ever possible) of the civilization.
Without literature, archaeology is really only a pile of buried rubble, and while we can make some educated guesses, simply looking at old buildings and rocks scattered across the ground tells us very little. If we are lucky enough to have some literature then those scattered rocks can come to life. However, the problem with literature without archaeology is that it can be difficult (if not impossible) to determine the accuracy of these writings, particularly since all writing subjective.
Having said that, I enjoyed reading this when I was 18 as it introduced me into realizing that not all we’re taught in school is all there is to know.