Delta blues music is arguably about the earliest types of "blues" music and is thought to have originated in the Mississippi Delta. The typical instruments used to play Delta Blues are the acoustic guitar and the harmonica. The first recordings of this music emerged in the late 1920s and, during the Depression, the harmonica dominated this musical sphere. The harmonica remains the most portable instrument used in traditional American folk and blues music. Although the first harmonicas date back to Germany in the mid-19th century, this seemingly simple musical instrument has become an icon in American music.