Mainly through ideas of Manifest Destiny, the idea that settlers had a god given right to expand with the manifest destiny. after the Louisiana purchase, the US bought land previously owned by the French. We made a purchase of the land, thus it was believed the land was ours, even if others were living on it. plus, the government of the time gave rewards in the land, for fighting the civil war. After the gold rush, more were expanding west for personal wealth, it became a common way of life. Much like the saying if everyone was jumping off a cliff would you, everyone was doing it, so many would not have found it hard to live on land that may have not truly been there's.
