These monuments were built mostly from the 1890-1930 during the worst period of extrajudicial killings of black people. White mobs freely enforced violent racial apartheid with the approval and backing of state and local governments. One example, in 1898 the elected government of the majority black city of Wilmington, North Carolina was overthrown in a coup by a white mob and several dozen black people and members of the local government were executed[1].
These statues are prominently displayed in front of court houses and government buildings in towns and cities all over the south. The governments that built these monuments were extraordinarily reprehensible in their explicit and violent racism.
[1] https://en.wikipedia.org/wiki/Wilmington_insurrection_of_189...