Ancient Sumerians Looked To The Heavens When They Invented The System of Time – And We Still Use It Today

It may appear strange that we split the hours into 60 minutes and the days into 24 hours – why not a multiple of 10 or 12? Simply put, the explanation is that the founders of time did not utilize a decimal (base-10) or duodecimal (base-12) system, but rather a sexagesimal (base-60) one. 60 was the ideal number for the ancient Sumerian thinkers who first split the motions of the sky into countable intervals.

The 60th Useful Number

The number 60 may be split into equal parts by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. Furthermore, ancient astronomers thought there were 360 days in a year, with 60 fittings nicely into six periods. The Sumerian Empire was short-lived. However, for almost 5,000 years, the world has been dedicated to its interpretation of time.


Plimpton 322, a well-known Babylonian mathematics tablet. Christine Proust and Columbia University are to be credited.

The Progression of Time

Many ancient cultures had a rough idea of how time passed. Obviously, a day began with the rising of the sun and a night began with the setting of the sun. The passing of weeks, months, and years was less clear, but they, too, had been estimated by ancient peoples. A month was the duration of one full lunar cycle, whereas a week was the duration of one phase of the lunar cycle. The changing seasons and the relative position of the sun might be used to calculate the length of a year. Scholars may tally the number of sunrises/sunsets that elapsed till the sun reached its zenith again after the zenith was known. The ancient Egyptians, Mayans, and Babylonians, among others, decided that the year had 360 days in this manner. However, it was Sumerian astronomers and mathematicians who first methodically divided time. Their work was extensively recognized and disseminated throughout Eurasia.


To record the passage of time, ancient civilizations turned to the stars.

The Decimal System Was Not the First Counting System

Today, the decimal system is the most commonly used number basis. Given that humans have ten fingers to count on, it is a simple counting method. As a result, various people claim to have invented the decimal system, including the Greeks (about 300 BC), the Chinese (100 BC), and the Indians (circa 100 AD). The roots of the duodecimal system are less well documented, while it appears to have originated separately in ancient Nigerian, Chinese, and Babylonian languages, particularly in the belief of the 12 signs of the zodiac. All of these, however, was predated by the Sumerians, who developed their sexagesimal system in the third millennium BC.

The Sexagesimal System Was Invented by the Sumerians

Because it was so readily divisible, the Sumerians first preferred the number 60. Not only were there few remainders when working with the number 60 and its multiples, but the remainders that did exist did not include repeated decimals (for example, 1/3 = 0.333…), which Sumerians could not comprehend at the time. The Akkadians invaded Sumer about 2400 BC, followed by the Amorites (commonly known as the Babylonians) in 1800 BC. Each succeeding governing power admired the simple sexagesimal system and integrated it into their own mathematics. As a result, the idea of dividing time into 60-minute increments remained and expanded to the East in Persia, India, and China, as well as the West in Egypt, Carthage, and Rome. The approach nicely supplemented the efforts of Chinese astronomers in discovering the 12 astronomical hours of the stars (a mostly theoretical discovery as most people lived by the sun). It also fits with imperial military methods, such as dividing the night watch into many equal portions. The Egyptians kept three watches each night, whereas the Romans kept four.


Babylonian tablet YBC 7289 depicting the sexagesimal number 1; 24, 51, 10, corresponding to 2

The 360 was determined to be not only the amount of time of the earth’s ideal orbit but also the correct measurement of a circle, according to Greek and Islamic geometric advancements. As a result, the sexagesimal system began to consolidate its position in history by becoming indispensable in mathematics and navigation (the earth is divided into degrees of longitude and latitude). Finally, when the watch was invented in the 14th century, the circular clock face was split into clean, sexagesimal quadrants that provided each minute 60 seconds.

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