What led to the term "Bleeding Kansas?"

when in 1854 the Kansas-Nebraksa Act overturned the Missouri Compromise's use of latitude as the boundary between slave and free territory and instead, using the principle of popular sovereignty, decreed that the residents would determine whether the area became a free state or a slave state. Proslavery and free-state settlers flooded into Kansas to try to influence the decision.

Bleeding Kansas is the term used to describe the period of violence during the settling of the Kansas territory.