Answer;
-the isolation of black Americans in the rural south
The powerfully expressive sound of early delta blues was in part due to the isolation of black Americans in the rural south.
Step-by-step explanation;
-The Delta blues is one of the earliest styles of blues music. It originated in the Mississippi Delta, a region of the United States that stretches from north to south between Memphis, Tennessee, and Vicksburg, Mississippi, and from east to west between the Yazoo River and the Mississippi River.
-It's generally accepted that the music evolved from African spirituals, African chants, work songs, field hollers, rural fife and drum music, revivalist hymns, and country dance music.