Final answer:
The early period of human history when simple stone tools were used is known as the Paleolithic Age or Old Stone Age. This period lasted from approximately 3.3 million years ago to about 12,000 years ago.
Step-by-step explanation:
The early period of human history in which humans used simple stone tools is called the Paleolithic Age, which translates from Greek as 'old stone.' This era is also known as the Old Stone Age and it marks the earliest and longest phase of human history. The earliest known human-made stone tools, likely created by Homo habilis, emerged about 2.6 million years ago, starting with the development of Oldowan tools. Subsequent to this, around 1.7 million years ago, early humans developed more sophisticated Acheulean tools. The Paleolithic Age is significant as it represents the genesis of human technology and culture, including the beginning of art and symbolic language.
Tools from this era served for cutting, scraping, and chopping purposes and were composed not only of stone but also occasionally of bone and wood. However, stone tools are the most prevalent archaeological find due to their durability over time, offering us the clearest evidence of early human ingenuity. The Paleolithic Age spanned a vast period from as early as 3.3 million years ago to about 12,000 years ago, and involved the evolution of various human societies which included the production of sophisticated language and the capacity for agriculture.