<P> With the arrival of Francisco Vázquez de Coronado, a Spanish conquistador, the first recorded history of encounter between Europeans and Native Americans in the Great Plains occurred in Texas, Kansas and Nebraska from 1540 to 1542 . In that same time period, Hernando de Soto crossed a west - northwest direction in what is now Oklahoma and Texas . Today this is known as the De Soto Trail . The Spanish thought the Great Plains were the location of the mythological Quivira and Cíbola, a place said to be rich in gold . </P> <P> Over the next one hundred years, founding of the fur trade brought thousands of ethnic Europeans into the Great Plains . Fur trappers from France, Spain, Britain, Russia and the young United States made their way across much of the region, making regular contacts with Native Americans . After the United States acquired the Louisiana Purchase in 1803 and conducted the Lewis and Clark Expedition in 1804--1806, more information about the Plains became available and various pioneers entered the areas . </P> <P> Manuel Lisa, based in St. Louis, established a major fur trading site at his Fort Lisa on the Missouri River in Nebraska . Fur trading posts were often the basis of later settlements . Through the 19th century, more European Americans and Europeans migrated to the Great Plains as part of a vast westward expansion of population . New settlements became dotted across the Great Plains . </P> <P> The new immigrants also brought diseases against which the Native Americans had no resistance . Between a half and two - thirds of the Plains Indians are thought to have died of smallpox by the time of the 1803 Louisiana Purchase . </P>

What plains stretch across the middle of the united states