Can someone please explain to me what exactly is happening at Standing Rock and why people are protesting?

a corporation bribed state governments and enough federal bureaucracy to keep federal law enforcement from being properly involved as the illegally "purchased" land from the states of north and south dakota despite the fact that it was the property of the sioux by two different treaties. since the sioux didn't invalidate the treaty the transfer of land from the tribe which is a sovereign entity to a private corporation by means of imminent domain was unlawful. Especially when you consider that imminent domain is only legal when the land is being taken for official government function which definition does not include the sale of land for profit to corporations. which is what happened.... that same corporation used the same method to rob thousands of farmers who didn't make national news because they didn't have the money for the legal fight. to make matters worse it is an obvious case of corruption since the governaer who authorized national guard involvment stands to make a lot of money from his shares in the oil company illegally making the pipeline. instead of excusing himself from any decisions due to conflict of interest he sent young men to lose their honor and possibly die.

The Dakota Indians are protesting against an oil pipeline that is going across their reservation and under 2 rivers.
The protest is to protect the land, water and religious/spiritual sites.

Still trying to screw the Indians over, even after all this time.

They want to run an oil pipeline through Indian territory, including an Indian sacred burial ground. There's a lot of money coming from getting that pipeline through, coming to owners and investors of big oil companies.

I honestly think they probably will.America is a unique country.Some of the states are as wealthy as countries and there is more than 50 of them.I can't see any other country taking their place.