Comparing the dates when Calendars began framing their respective histories.
source:
Reingold, Edward M and Nachum Dershowitz. Calendrical Calculations – the Ultimate Edition. Cambridge University Press. New York, 2018.
| Calendar | Epoch RD | Equivalents |
| Julian Day Number | -1721424.5 | Nov 24, -4713 (GC) Jan 1, 4713 BCE (JC) |
| Hebrew | -1373427 | Sep 7, -3760 (GC) Oct 7, 3761 BCE (JC) |
| Mayan | -1137142 | Aug 11, -3113 (GC) Sep 6, 3114 BCE (JC) |
| Hindu Kali Yuga | -1132959 | Jan 23, -3101 (GC) Feb 18, 3102 BCE (JC) |
| Chinese | -963099 | Feb 15, -2636 (GC) Mar 8, 2637 BCE (JC) |
| Samaritan | -598573 | Mar 3, -1638 (GC) Mar 15, 1639 BCE (JC) |
| Egyptian | -272787 | Feb 18, -746 (GC) Feb 26, 747 BCE (JC) |
| Babylonian | -113502 | Mar 29, -310 (GC) Apr 3, 311 BCE (JC) |
| Tibetan | -46410 | Dec 7, -127 (GC) Dec 10, 128 BCE (JC) |
| Julian | -1 | Dec 30, 0 (GC) Jan 1, 1 CE (JC) |
| Gregorian | 1 | Jan 1, 1 (GC) Jan 3, 1 CE (JC) |
| ISO | 1 | Jan 1, 1 (GC) Jan 3, 1 CE (JC) |
| Akan | 37 | Feb 6, 1 (GC) Feb 8, 1 CE (JC) |
| Ethiopic | 2796 | Aug 27, 8 (GC) Aug 29, 8 CE (JC) |
| Coptic | 103605 | Aug 29, 284 (GC) Aug 29, 284 CE (JC) |
| Armenian | 201443 | Jul 13, 552 (GC) Jul 11, 552 CE (JC) |
| Persian | 226896 | Mar 22, 622 (GC) Mar 19, 622 (JC) |
| Islamic | 227015 | Jul 19, 622 (GC) Jul 16, 622 CE (JC) |
| Zoroastrian | 230638 | Jun 19, 632 (GC) Jun 16, 632 CE (JC) |
| French Revolutionary | 654415 | Sep 22, 1792 (GC) Sep 11, 1792 CE (JC) |
| Bahá’í | 673222 | Mar 21, 1844 (GC) Mar9, 1844 CE (JC) |
| Modified Julian Day | 678576 | Nov 17, 1858 (GC) Nov 5, 1858 CE (JC) |
| Unix | 719163 | Jan 1, 1970 (GC) Dec 19, 1969 CE (JC) |
JC = Julian Calendar
Rethinking Time 