The correct answer is Native Americans and Patriots.
During the era of westward expansion (early-mid 19th century) the United States was trying to achieve its goal of manifest destiny. The federal government believed it was America's god given right to control all of the land in the North American continent. As the US continued to expand and tried to take over new territories, many Patriots (American citizens) were conflicting with Native Americans. This is due to the fact that Americans were often encroaching on Native American land.