Complex sentence: Morgan was one of the original 29 members of the Niagara Movement, a civil rights organization founded by Du Bois in 1905; it was the precursor to the National Association for the Advancement of Colored People (NAACP).
Split into simpler sentences: Morgan was one of the original 29 members of the Niagara Movement, a civil rights organization founded by Du Bois in 1905. The Niagara Movement was the precursor to the National Association for the Advancement of Colored People (NAACP).