Complex sentence: The Fremont culture or Fremont people, named after the Fremont River in Utah where many of the first Fremont sites were discovered, is a culture believed to have inhabited what is now Utah and parts of Nevada, Idaho and Colorado from 700 to 1300 AD.
Split into simpler sentences: The Fremont culture or Fremont people is a Precolumbian archaeological culture taking its name from the Fremont River in Utah where the first Fremont sites were discovered. It inhabited sites in what is now Utah and parts of Nevada, Idaho and Colorado from 700 to 1300 AD.