Folk Customs
Ethnic Customs
The peoples who are vulgar aren't refined city folk. They're people with folk customs and ethnic customs.
みんぞく
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
彼は、歴史民俗資料館の館長です。
He is the director of the Museum of History and Folklore.