Many of the Early American settlers bought property from the Indians. The Early Americans who first settled in America were a peace-loving freedom desiring people. Yes, they were peaceful and believed in the cause of freedom so much that if necessary, they would fight to keep it. With the Early Americans, much like today, there were other people who came into our country. Many of them were not seeking freedom or trying to build a community. Quite a few came over to find gold. These people were really like Adventurers. Their goal was different than those who came over here to start a country where we could have the freedoms we have today.
One such incident was that of the California Gold Rush. Many knew that there was gold to be found here. Many came in from different countries. I have read, but don't know for sure, that these miners were cruel to the Native Americans. Supposedly, these miners had many Native Americans killed. They wanted them exterminated. This is awful, if it really happened. But.... the people who were doing this horrible crime were not the Early American settlers who founded our country. They were people who came over here to find gold. They were greedy. They wanted to get rid of anything that got in their way of finding gold (I want to be careful to note that probably not all the California Gold Rush miners were like this).
In every group of people there will be some bad. That's why we need the standard of God in our communities. We can say whatever we want to or do whatever we want, but, we are accountable to God after death. We will be judged according to His standard.
On a good note remember David Brainerd. He was one of my favorite Early American History figures. He made friends with the Native Americans and even translated the Bible into their language for them! David Brainerd was a friend to the Native Americans around him. He truly loved them. When he was 28, he was found dead from tuberculosis. He was praying while he was dying. (On another interesting note, I believe that David Brainerd was engaged to one of Jonathan Edward's daughters.)
There was also a couple named the Whitmans who preached and served the Native Americans, I believe in the Northwest part of the U.S. A terrible plague broke out and was killing the Native Americans, but Marcus and Narcissa Whitman were resistant to the disease. They nursed many Native Americans back to health because they were in a place where they could help and not get sick. Some of the Native Americans became suspicious though, because of the fact that they weren't getting sick. They thought the Whitmans were the ones making the Native Americans get the disease, so they had the Whitmans killed.
https://www.whitman.edu/alumni/be-connected/whitman-traditions/marcus-and-narcissa-whitman