What events led to "Bleeding Kansas"?

Bleeding Kansas, Bloody Kansas, or the Border War was a series of violent civil confrontations in Kansas Territory, and to a lesser extent in western Missouri, between 1854 and 1859. It emerged from a political and ideological debate over the legality of slavery in the proposed state of Kansas.

Explanation:

norsemen from northern countries had made earlier journeys

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.