sentences:  By the early 20th century the Hill District's Jewish presence became less prominent as the neighborhood became a hub for African-American culture.More than 24,000 "negro" immigrants arrived from 1850 to 1900  and concentrated in the Hill District.By the 1920s and 30s it was known for its eclectic jazz clubs and speakeasies, often covered in the pages of the "Pittsburgh Courier" by writers like Frank E. Bolden.