What procedures did ancient people need to go through to immigrate?

In ancient times, there were no national boundaries. If you want to go abroad, you can go by carriage or ship. When you go to another country, if you can understand or speak the language of another country, you can live there. Unlike we need passports to go abroad now, we need Hong Kong, Macao and Taiwan passes. In ancient times, you can go directly without going through any formalities, if you have the conditions.