Complex sentence: The Klamath River's name was recorded by Europeans in the 19th century derived from the word "klamet" or the Klamath Tribe, but prior to white contact, many names were used to refer to the river, including "Ishkêesh" and "Koke".
Split into simpler sentences: The Klamath River's name was recorded by Europeans in the 19th century derived from the word "klamet" or the Klamath Tribe. Prior to European contact, the river was called by many different names, including "Ishkêesh" and "Koke".