system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: How do we know that historically accurate things are.. historically accurate?

Let's go back to the 1600's. Stuff happened. How do we know this stuff happened - the way people dressed, ate, acted? Is it a collective of surviving evidence gathered from the time? How do we know that written statements from the time period weren't bullshit? Do we just agree that we can form a general picture of what happened in the past from the surviving evidence? 

(1600s used as an example, this applies to general history. I assume things get more questionable the further you go back) 

Thank you for indulging a historically-challenged idiot who's had a few whiskeys.
gpt
As with any time in history, you rely on corroborating evidence. If you only find one thing indicating something, you're completely correct that it could be fabricated, exaggerated, or in some way false. But if you have many pieces of evidence from various sources that all state the same thing, it raises the confidence level in regards to accuracy. Best if you can find evidence from independent sources which may not share the same cultural biases.

Sometimes you can't find this kind of supporting evidence, in which case you might make note of it in case something new shows up to support it. You also have to account for bias since, as the saying goes, history is written by the victors. It can be challenging, as often times the stories of the losing side are destroyed or forgotten, and thus historians may never have a full, complete picture of some events.