A Capella

Civilization without instrumentalities? That would be the Four Preps. They wrote the immortal Santa Catalina:

Twenty- six miles across the sea

Santa catalina is a-waitin' for me

Santa catalina, the island of romance, romance, romance, romance
Water all around it everywhereTropical trees and the salty air

But for me the thing that's a-waitin' there-romance

The Four Preps also appeared in Gidget and one of them wrote Cobb wrote the song "Tainted Love" for Gloria Jones, which became a worldwide hit for Soft Cell in 1982. (Source: Wikipedia).