Today we count years in one long line: 1999, 2000, 2001. Egyptians did not. They dated documents by the king: "Year 5, second month of the harvest season, day 10, under the Majesty of King So-and-so." When a new king came to the throne, the count started again at Year 1.
Key idea
Egyptian dates are regnal years: years of a king's reign. To turn them into years BC, historians must know the order of the kings and the length of each reign, and add them up king by king. Co-regencies (two kings ruling together) and gaps make this hard.
Why it works
A regnal date tells you how far into one reign an event fell, but nothing about how long ago that reign was. To place it on our calendar, you need a chain: the lengths of all the reigns between it and some king whose date is known from another source. Each link in the chain has its own uncertainty, so errors add up the farther back you go.
Adding up reigns
Worked example: An imaginary dynasty
Imagine three kings who ruled one after another. King A ruled 20 years, King B 12 years, King C 30 years. If King A's Year 1 was 1500 BC, in what year BC was King C's Year 1?
- King A's 20 years run from 1500 to 1481 BC (Year 1 is 1500, so Year 20 is 1500 − 19 = 1481).
- King B's Year 1 is the next year, 1480 BC; his 12 years run to 1469 BC.
- King C's Year 1 is the next year, 1468 BC. Shortcut: 1500 − (20 + 12) = 1468.
Answer: 1468 BC (in this imaginary example).
Real cases are messier. Reigns were counted in whole years, so the last part-year of one king and the first of the next can overlap. Some kings named their sons as co-rulers, so for a few years two reigns ran at once; how long some co-regencies lasted is still debated. And many reign lengths are missing from the king lists.
| Part | Example | Meaning |
|---|---|---|
| Year | Year 5 | the 5th year of the reign |
| Season | akhet, peret, shemu | inundation, growing, harvest |
| Month | month 2 | each season had 4 months of 30 days |
| Day | day 10 | the day of the month |
Common mistake
Expecting a continuous era like BC and AD. Each reign restarted the count. And because of co-regencies, simply adding all reign lengths can count some years twice. A check: does any king's reign overlap with the one before?