[duo797]

My impression was that a number of family names were places where people came from, similar to how hundreds of years ago what we take to be surnames were really just saying 'Person of So-and-so city' like how 'Leonardo da Vinci' (probably misspelled a bit) is just 'Leonardo of Vinci'. Similarly someone with the family name 川口 might have had ancestors who lived in an area at the mouth of a river.

Would anyone with more experience in japanese family names and history care to confirm or deny this for me? It's an assumption I carry and if it's wrong I'd love to know so I don't continue.