Innovation No. 13 of 77 in the book
The Calendar
A 365-day year created by observing the Nile’s flood cycle
- When
- c. 3000 BCE
- Dynasty
- 1st Dynasty
- Era
- Early Dynastic Period
The 365-day year you live by was worked out on the Nile by around 3000 BCE, at the dawn of the dynasties.
Egyptians tied it to the sky: the year began when the star Sirius rose at dawn just before the Nile’s annual flood. Twelve months of 30 days, plus five extra days, made 365.
It was so clean and predictable that Julius Caesar borrowed it in 46 BCE to fix Rome’s broken calendar — giving us the one we still use.
The shape of your year was set beside a flooding river five thousand years ago.
Frequently Asked Questions
What is the earliest archaeological evidence for the calendar in ancient Egypt?
The earliest confirmed evidence dates to approximately 3000 BCE during Egypt's Early Dynastic (1st Dynasty). The 365-day year you live by was worked out on the Nile by around 3000 BCE, at the dawn of the dynasties.
How did ancient Egyptians develop the calendar, and what is its legacy?
Egyptians tied it to the sky: the year began when the star Sirius rose at dawn just before the Nile’s annual flood. Twelve months of 30 days, plus five extra days, made 365. Egyptians tied it to the sky: the year began when the star Sirius rose at dawn just before the Nile’s annual flood. Twelve months of 30 days, plus five extra days, made 365. The shape of your year was set beside a flooding river five thousand years ago.