system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When Europeans came to Africa and The Americas, how did they communicate with the locals?

Considering that no one knows the other's language.
gpt
"Immersion" is a great way to learn a language fast. Move to another country, and refuse to speak in anything but the local language. Within a month or two, you'll be good enough at it to get by. 

So if the first group people to meet stayed together long enough, some people on each side would relatively quickly be able to communicate to some extent.