Answer:
They were dissatisfied with poor reservation conditions.
Step-by-step explanation:
The Native Americans initially agreed to be reallocated to the nearby reservations in exchange of giving up their ancestral lands to the government.
But At the time, the government did not make a good effort to provide the Native Americans with proper standard of living. They have to face problems such as insufficient food, small spaces, and unmaintained environment. So, they decided to raid nearby white settlement as a response.