A stone tool that was shaped and used for various purposes by people known as Homo Eractus, who lived between approximately 1,240 and 1,170 million years ago, was found in the alluviums accumulated by the Gediz River in this valley. This tool, which is 6 cm long and 4 cm wide and made of a stone called quartzite, was found by chance by Turkish, British and Dutch geoscientists within the scope of scientific studies carried out in this region for 20 years. This stone tool has great importance in terms of the prehistoric history of Western Anatolia. Before this tool was discovered, the oldest traces of human history in western Anatolia dated back to 510 thousand years ago. With the discovery of this tool, traces of prehistoric humans have gone back much further, 1.2 million years ago.

Although it is a widely accepted fact that humans first spread from the African continent to Europe, Asia and the Americas, there is no consensus among scientists regarding the possible routes and timing of this migration. With the discovery of this human stone tool in the Gediz valley, it was revealed that the people of the Paleolithic Period used the Anatolian Peninsula as a route when migrating from Africa to Eurasia, and one of the migration routes on Anatolia was the Gediz Valley. In terms of timing, it has been demonstrated with great accuracy that this migration took place between 1,240 and 1,170 million years ago.

Although some human-made tools belonging to the Paleolithic Period had previously been found in Western Anatolia, there were some inconsistencies between the views put forward about their ages. For this reason, our knowledge about the oldest periods of human history in the Anatolian peninsula remains insufficient.