In the Old Japanese Cedar Tree chronology the year 550 CE marks the beginning of a catastrophic drop in the D/H ratio.
Arguably, this 1st millennium outlier event was caused by inbound debris from space.
The Justinian Comet of 535 AD ushered in a period of about 135 years during which Justinian’s Raging Bulls wreaked havoc across the globe.
If that was the case then the associated atmospheric debris would probably have triggered a sustained nuclear winter style event that lowered surface temperatures.
The nuclear winter scenario assumes that 100 or more city firestorms are ignited by the nuclear explosions of a nuclear war, and the firestorms lift large enough amounts of sooty smoke into the upper troposphere and lower stratosphere, soot lifted by the movement offered by the pyrocumulonimbus clouds that form during a firestorm.
At 10–15 kilometres (6–9 miles) above the Earth’s surface, the absorption of sunlight could further heat the soot in the smoke, lifting some or all of it into the stratosphere, where the smoke could persist for years, if there is no rain to wash it out.
This aerosol of particles could heat the stratosphere and block out a portion of the sun’s light from reaching the surface, causing surface temperatures to drop drastically, and with that, it is predicted surface air temperatures would be akin to, or colder than, a given region’s winter for months to years on end.
In the Arabian Peninsula the onset of this catastrophic drop in the D/H ratio may have occurred in the Year of the Elephant 570 CE.
Abrahah’s army was totally destroyed on its march – by an extremely huge flock of martin swallow birds that dropped tiny stones onto them and turned them to ashes – and Abrahah himself died on his return to Sana.
The anniversary of the Year of the Elephant became a “reference point” for counting years and in 644 CE the count was recalibrated to start in 622 CE for the Islamic calendar.
The fact that it is the year of Prophet Muhammad’s birth made the Year of the Elephant even more important and the early Muslim community appears to have continued using the Year of the Elephant as a calendrical reference point.
Caliph ‘Umar (d. 644 CE ) changed that practice, identifying the Prophet’s pilgrimage from Mecca to Medina (622) as the beginning of the Islamic calendar.
The Qur’an: an Encyclopedia – Oliver Leaman (Editor) – 2006
In the Roman Republic a calendar adjustment event occurred in 45 BCE.
The Roman calendar changed its form several times between the founding of Rome and the fall of the Roman Empire.
The regular calendar had only 355 days, which meant that it would quickly be unsynchronized with the solar year, causing, for example, agricultural festivals to occur out of season.
The Julian calendar, introduced by Julius Caesar in 46 BC (708 AUC), was a reform of the Roman calendar.
It took effect in 45 BC (AUC 709), shortly after the Roman conquest of Egypt.
It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was refined and gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII.
The Julian calendar has a regular year of 365 days divided into 12 months.
A leap day is added to February every four years.
The Julian year is, therefore, on average 365.25 days long.
“ab urbe condita” (related to “anno urbis conditae”; A. U. C., AUC, a.u.c.; also “anno urbis”, short a.u.) is a Latin phrase meaning “from the founding of the City (Rome)”, traditionally dated to 753 BC.
AUC is a year-numbering system used by some ancient Roman historians to identify particular Roman years
However, the Realigned Roman Time Line [based upon Gunnar Heinsohn’s central theme that the mainstream narrative for the 1st millennium only covers 300 years of history] indicates the Year of the Elephant and the introduction of the Julian calendar are [almost] contemporaneous events associated with the Arabian Horizon.
Therefore, some 700 years of the 1st millennium (230 to 930s) have neither strata nor tree samples for C14 or dendro-chronological dating.
Archaeological Strata Versus Baillie’s Tree-Rings: Proposal for an Experiment
Gunnar Heinsohn – 8 September 2014
In other words:
The Heinsohn Sandwich contains 277 years of history that are wedged between the Arabian Horizon [637 CE] and the Heinsohn Horizon [914 CE].
In essence, these 277 years in the Heinsohn Sandwich provide most of the 300 years worth of history the mainstream has [somehow] smeared across a 1,000 years in the 1st millennium.
The implication of the Heinsohn Sandwich is that the Arabian Horizon [637 CE] represents a dramatic loss of historical records and knowledge.
Put another way:
When the Western historians in the 2nd millennium recovered their senses [after the disruptions following the Heinsohn Horizon – 914 CE] their knowledge of the 1st millennium was largely limited to the contents of the Heinsohn Sandwich.
And being creative fellows [who didn’t want to admit defeat or ignorance] these early 2nd millennium historians began to selectively smear 300 years worth of knowledge [and creative writing] across the entire 1,000 years of the 1st millennium.
Working backwards through the mainstream historical narrative we arrive at the Heinsohn Horizon in the 930s where the mainstream narrative falls into the Academic Abyss and degenerates into fiction, fantasy and fabrication for a period of 700 [phantom] years.
However, where there are neither strata nor tree samples the myopic mainstream has managed to unearth an estimated 269,636 European manuscripts in the Academic Abyss.
Furthermore, these Western historians in the 2nd millennium weren’t interested in 2nd place provenances so [amongst other historical fictions] they created the highly unconvincing Anno Domini story whereby Roman clerics:
1) Waited around for 500 years before they got round to inventing Anno Domini.
2) Waited another 500 years before they got round to popularising Anno Domini.
The Anno Domini (AD) year numbering was developed by a monk named Dionysius Exiguus in Rome during 525, as a result of his work on calculating the date of Easter.
According to the Catholic Encyclopedia, popes continued to date documents according to regnal years for some time, but usage of AD gradually became more common in Roman Catholic countries from the 11th to the 14th centuries.
At least, on the plus side:
The 2nd millennium historians writing about the Byzantine Empire had the good sense to delay the adoption of the Byzantine calendar until after the Heinsohn Horizon.
The Byzantine calendar, also called “Creation Era of Constantinople” or “Era of the World” was the calendar used by the Eastern Orthodox Church from c. 691 to 1728 in the Ecumenical Patriarchate.
It was also the official calendar of the Byzantine Empire from 988 to 1453, and of Kievan Rus’ and Russia from c. 988 to 1700.
However, other 2nd millennium historians weren’t so sensible [or lucky]…