Water is a polar molecule and also acts as a polar solvent. When a chemical species is said to be "polar," this means that the positive and negative electrical charges are unevenly distributed. The positive charge comes from the atomic nucleus, while the electrons supply the negative charge.
Well one was the boxer rebellion
During the ensuing decades, the abolitionist movement grew in Northern states, and Congress regulated the expansion of slavery as new states were admitted to the Union. Britain banned the importation of African slaves in its colonies in 1807 and abolished slavery in the British Empire in 1833.
After a little while Lewis and Clark viewed them as slightly helpful with the more time they spent around/with them, because they introduced new methods with medicine, weapons, food, etc.
They had to defend themselves against raids by other clans who wanted water, livestock, or food supplies.