There is no "real" history if by "real" you mean a document or source- some piece if evidence that can tell us about the past without the contextualization.

Even if something is not outright propaganda, its production, its meaning, etc, are all circumscribed by cultural-temporal-spacial context.

Honestly, sometimes propaganda pieces- or ones written with obvious biases, in my case promotional material for overseas colonial expansion, can be easier to mediate because the context/intent of the author is simply more clear.
Though, for someone who might not be able to recognize that this material is has obviously been created with an agenda in mind, it could be very misleading. This is one of the tools you develop as a historian and familiarizing yourself with an event, regional, or methodology. You learn to question, probe, and analyze the production and consumption of information; you immerse yourself in a particular world so you know what questions to ask of your sources. Familiarity is definitely key- while I can situate Pacific sources in their proper context- I would likely not be be able to do so for Ming China with any certainty.

It's also worth noting that sometimes the propaganda tells a story just by being propaganda in the first place. For instance, by his own history, the Maya ruler Bird Jaguar IV of Yaxchilan was the rightful heir to his father's throne. But if you look at prior records, you see that Bird Jaguar IV's mother doesn't appear in any texts before his reign, and that there's several years between his father's death and his own accession. One may also note the huge number of historical events Bird Jaguar recorded compared to his predecessors. There was a reason he needed to promote this idea of his legitimacy, and it certainly wasn't because it was uncontested.