The Sumerians were the people of southern Mesopotamia whose civilization flourished between c. 4100-1750 BCE. Their name comes from the region which is frequently – and incorrectly – referred to as a “country”. Sumer was never a cohesive political entity, however, but a region of city-states each with its own king.

Sumer was the southern counterpart to the northern region of Akkad whose people gave Sumer its name, meaning “land of the civilized kings”. The Sumerians themselves referred to their region simply as “the land” or “the land of the black-headed people”.

In the biblical Book of Genesis, chapter 1, it states that God divided the night from the day and saw that it was good. If one accepts God’s role in creating day and night then the Sumerians finished the job and, if one does not, it was not God who divided night and day – it was the Sumerians.

The Sumerians were responsible for many of the most important innovations, inventions, and concepts taken for granted in the present day. They essentially “invented” time by dividing day and night into 12-hour periods, hours into 60 minutes, and minutes into 60 seconds.

Their other innovations and inventions include the first schools, the earliest version of the tale of the Great Flood and other biblical narratives, the oldest heroic epic, governmental bureaucracy, monumental architecture, and irrigation techniques.

How did we come to divide the hour into 60 minutes and the minute into 60 seconds? These smaller divisions of time have been in practical use for only about 400 years, but they were vital to the advent of modern science.

For millennia, ancient civilizations looked to the sky to measure the big units of time. There’s the year, which is the time it takes Earth to complete one orbit around the sun; the month, which is approximately how long it takes the moon to orbit our planet; the week, which is approximately the time between the four phases of the moon; and the day, which is the duration of one rotation of the Earth’s on its axis.

Dividing the day was not so straightforward, though hours and minutes have their origins in traditions tracing back thousands of years.

The use of 60 began with the Sumerians who used different number systems. While you and I write numbers using base 10, or “decimal” this civilization used base 12 (“duodecimal”) and base 60 (“sexigesimal”).

Twelve was an important number to the Sumerians, and later to the Egyptians. For example, it was the number of lunar cycles in a year and the number of constellations of the Zodiac. Day and night were each divided into 12 periods, and the 24-hour day was born.

In the 24th century B.C., the Sumerians were conquered by the Akkadians, who then fell to the Amorites, who rose to power and built the nation-state of Babylon, which peaked in the 18th century B.C. The Babylonians invented the degree and defined a circle as having 360 degrees. There are a couple of theories as to why they chose 360:

The Babylonians understood a year as having close to 360 days; hence the sun “moves” along the ecliptic approximately 1 degree per day.

The radius of a circle maps onto a circumscribed hexagon of six equilateral triangles, and thus a sixth of a circle forms a natural angle measure. In the numerals inherited from the Sumerians, a number’s sexagesimal value was inferred from context, so six was “spelled” the same way as 360.

Today, 5,000 years after the Sumerians first began using 60, we divide our days by hours, minutes and seconds. In recent years, we have changed how the units are measured.

No longer derived by dividing astronomical events into smaller parts, the second is now defined on the atomic level. Specifically, a second is the duration of 9,192,631,770 energy transitions of the cesium atom.

In their many inventions and innovations, the Sumerians lay the groundwork for so many advancements in the daily lives of human beings that, today, it is impossible to imagine life without these things. Somehow, the people of Sumer were able to imagine things which had never existed on earth before and, in expressing their imaginations, invented the future.