system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 how did people come up with names for countries?
gpt
It's very arbitrary! 

E.g.

France - the region around France has had a few names through history, but at some point it was the Kingdom of the Franksz the Franks being the name of Germanic tribes near the (present day) German border. "France" came from this.

So although France has had many names, this name stuck and was picked up as France centralised and became an actual nation, as opposed to a vague region inhabited by different groups.

New Zealand - Abel Tasman was the first European to discover NZ, he was Dutch and Dutch cartographers later named the land after the Zeeland Provence of the Netherlands. Interestingly it was the Brits, not the Dutch, who settled (alongside the Maori) in NZ. But early Maori and British documents took "New Zealand" as the name of the new land.

Aotearoa - NZ's other name - translates to the "land of the long white cloud" which is what Maori originally called the North Island. It was later adapted to cover the whole country. There may not have been a name for the whole present day NZ - it was more or less all the people knew do why would they need to differentiate it. This was true pretty much everywhere, why would a villager in modern day France care about more than the nearest towns or major cities of whoever ruled them at the time.

China - China is actually a European name that was given to China with Persian origin, based on fairly limited trade and relations with the country. In Chinese, China is called "The Middle Country", because the nation has thousands of years of civilisation and for much of which, was the middle of the world it knew.

It's important to understand that the nation state as we know it today is a fairly modern concept. Somewhere between the 1600-1900s many of the countries we know today sprung into formal existence, and as they did so they had to pick a name. That name was typically just whatever made the most sense at the time.