In the given quotation, the "they" referred to are the **Sumerians**. The Sumerians are credited with establishing a number system based on six, which led to dividing the hour into 60 minutes and the circle into 360 degrees. This numerical system, known as the sexagesimal system, has had a lasting impact and is still used today in measuring time and angles.
The Sumerians were an ancient civilization that flourished in Mesopotamia, known for their advancements in various fields such as mathematics, astronomy, and writing (cuneiform). Their contributions to mathematics, including the development of the base-60 numerical system, laid the foundation for many aspects of modern mathematics and timekeeping.
Therefore, in the context of the quotation provided, the "they" who established the numerical system based on six and its subsequent divisions into 60 minutes and 360 degrees are the Sumerians.
