The original Ku Klux Klan was formed by a bunch of young men who had served in the Confederate Army. They were young fools who wanted to have some fun. The fellow in charge of initiations was titled the Grand Turk, which suggests the kind of "fun" they would have had. They were like a college fraternity, a bunch of assholes in their late teens and early twenties.
They liked dressing up as ghosts and scaring people, especially Blacks. Many people in the nineteenth century south, Mary Chestnutt, the white diarist included, believed in ghosts. Have you ever been out in the real country at night. It wouldn't be hard in such no existent light to see someone dressed in a sheet as a ghost.
The KKK of the 1860s quickly turned into a terrorist organization, and was forced to disband.
AND THEN D.W. Griffith turned a novel called "The Clansman" into "Birth of a Nation". The KKK were shown as saviours of the south and of the white race. They dressed in robes inspired by the Spanish penitential societies, not like the original Klansmen, whose robes were vastly more original.
An enterprising soul, his name escapes me, decided to revive the KKK as a fraternal organization, like the Elks or the Shriners. He sold them robes like those worn in Griffith's movie. So was born a nasty tradition.
There is no 1 Ku Klux Klan at present. There are several organizations calling themselves the KKK. They don't get along with each other, raid each other for members, and fight among themselves. A local chapter spoke from the courthouse steps some years back. They used the most appallingly FOUL language I have ever heard in my life. Which of course, kept press coverage of the event to a minimum.