Complex sentence: The United States census of 1890 showed a total of 248,253 Native Americans living in America, down from 400,764 Native Americans identified in the census of 1850.
Split into simpler sentences: The United States census of 1890 showed a total of 248,253 Native Americans living in America. This number was down from the total of 400,764 Native Americans who had been surveyed in the census of 1850.