Question: Given the following passage  "The second part of the novel deals with what book reviewer Harding LeMay termed "the spirit-corroding shame of the civilized white Southerner in the treatment of the Negro". In the years following its release, many reviewers considered To Kill a Mockingbird a novel primarily concerned with race relations. Claudia Durst Johnson considers it "reasonable to believe" that the novel was shaped by two events involving racial issues in Alabama: Rosa Parks' refusal to yield her seat on a city bus to a white person, which sparked the 1955 Montgomery Bus Boycott, and the 1956 riots at the University of Alabama after Autherine Lucy and Polly Myers were admitted (Myers eventually withdrew her application and Lucy was expelled, but reinstated in 1980). In writing about the historical context of the novel's construction, two other literary scholars remark: "To Kill a Mockingbird was written and published amidst the most significant and conflict-ridden social change in the South since the Civil War and Reconstruction. Inevitably, despite its mid-1930s setting, the story told from the perspective of the 1950s voices the conflicts, tensions, and fears induced by this transition."",  answer the following question. Note that the answer is present within the text.  Question: What was the historical background behind To Kill a Mockingbird?
Answer:
the most significant and conflict-ridden social change in the South since the Civil War and Reconstruction