Did the Great Plains Indians attacked white settlers as early as the 1800's?

Yes, the Great Plains Indians did attack white settlers as early as the 1800s. Tensions escalated as settlers encroached on their lands, leading to conflicts such as the Sand Creek Massacre in 1864 and various skirmishes throughout the 19th century. These attacks were often responses to broken treaties, loss of resources, and threats to their way of life. The interactions between the Plains Indians and white settlers were marked by violence, resistance, and significant cultural clashes.