i think its the stone age because they were inventive in this period of time?
" the stone age -a prehistoric period when weapons and tools were made of stone or of organic materials such as bone, wood, or horn."
"Flint was used in the manufacture of tools during the Stone Age as it splits into thin, sharp splinters called flakes or blades (depending on the shape) when struck by another hard object (such as a hammerstone made of another material). This process is referred to as knapping."
hope this helps :)