system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: in ancient times, how did people know if people truly who they declared that they were?

In terms of royal ambassadors or members of courts and parliaments, when someone asks, “who goes there?” or “what business do you have with the lord?” how do the guards or officials know whether the other person is lying or not if they’ve never met them before and banners or papers and officials seals can be forged or duplicated?
gpt
99% of the time, any foreign dignitary would have given weeks of advance notice before they arrived. They would be accompanied by courtiers, guards, servants, tons of luggage, chefs, and all sorts of other people and things, all of which would be marked with the correct seals and paperwork. Pretending to be a member of the royal court, or of the noble class, would be difficult in any convincing manner. It was a **big** affair. 

And the receiving party would have made a great deal of preparations for them. Parties and feasts withstanding, the courtiers of the receiving party would have already learned all of the likes and dislikes of their guests, the proper introductions, manners, and all of those little formalities. 

Combine that with all of those noble families actually knowing each other throughout their lives, having partied with them for years, having learned about them during their adolescence (because they absolutely couldn't be caught in a socially awkward situation, that would be a huge faux pas), and so much more.

It's not like they just threw some farmers together to receive a noble guest. It was a big deal. 

**It was** possible to pretend to be some very minor, distantly related member, or even a member of some exotic court (a Jamaican prince to England during the 15th century, maybe), but you'd have to be a decent actor with some decent forgers.