How to target specific small markets based on ethnicity?

This might be a little out there, but I believe this would work…

I know two facts are true.
1. People Google themselves and their last names all the time.
2. Facebook has over 700 million members.
…both allow advertising…

You need a database of surnames for the Google AdWords advertising. Use broad match on the last name, and if you start seeing many clicks without conversions there might be a celebrity with a particular last name..

You can find the exact country/state/city with large ethnic populations and their associated interests. Or do a campaign just for those with the interest of ethnic activities…

One suggested population (Welsh) on Facebook:

4,840 people
who live in the United States
age 18 and older
who like welsh, welsh language, welsh rugby union, welsh rugby team, being welsh or welshbikerscouk

That is a small population, however with the Welsh decent cities, you could rapidly increase that number. I would also suggest splitting the campaigns from Welsh interests and city to see which do best. A simple flag image, or the word Welsh in a contrasting color outline…