On BC Dates as per BC Dating (quora)

Q I

As we know that 500 BC (Before Christ) means 2500 years ago. My question is 2500 years ago they used to write down 500 BC or some other date? Were they aware of Christ so that they were writing 500 BC? Sorry for my poor English.
https://www.quora.com/As-we-know-that-500-BC-Before-Christ-means-2500-years-ago-My-question-is-2500-years-ago-they-used-to-write-down-500-BC-or-some-other-date-Were-they-aware-of-Christ-so-that-they-were-writing-500-BC-Sorry-for-my-poor/answer/Hans-Georg-Lundahl

Hans-Georg Lundahl

Self Employed at Writer and Composer

Answered 9m ago

I don’t think even the prophet Daniel would have written 500 BC.

Your English is OK, by the way.

Romans would perhaps already have counted ab Urbe condita. Year 254 after founding of the city, or perhaps year 10 after chasing away Tarquin the Haughty.

Greece could be divided in year after Sicyon (AM 3237 in Syncellus = 2263 BC, so 1763 after Sicyon), years after first king of Argives, Inachus, (AM 3691 in Syncellus = 1808 BC, so 1308 after Inachus) after Cecrops founded Athens (AM 3945 in Syncellus = 1555 BC, so 1055 after Cecrops), more generally Fall of Troy (AM 4328 in Syncellus = 1172 BC, so 672 after Fall of Troy - according to one of the reckonings, the one used by Syncellus), founding of Corinth (yes, Homer makes an anachronism in Iliad, unless he means Sicyon) (AM 4428 in Syncellus = 1072 BC, so 572 after founding of Corinth), or, same year, of Sparta. To bring in some commonality of interest, 3:rd year of 69th Olympiad.

Further East, you would probably have been counting ninth regnal year of Darius of Persia.

Q II

Why do we count years backward in BC and then forward in AD?
https://www.quora.com/Why-do-we-count-years-backward-in-BC-and-then-forward-in-AD/answer/Hans-Georg-Lundahl

Quora Question Details Bot

Aug 8

Did people who lived in the BC days, actually count their years backward? Who thought of this convention? Sure, it's supposed to revolve around the birth of Christ but it didn't exactly and even then, it's confusing as hell. I dunno, why not just have the birthplace of civilization like Mesopotamia or something be year 0 and then move forward from there. So 2014 today would be year 5000 something or 6000 something. Doesn't that make more sense?

Hans-Georg Lundahl

Self Employed at Writer and Composer

Answered 39m ago

"Why do we count years backward in BC and then forward in AD?"

Second half first : Because counting forward in normal for any period, and because the period AD is one very useful one for avoiding to start all over again each time there is a new ruler. AD has been used since around 6th or 7th C. and gaining ground since perhaps two hundred years later.

First half : this started 16th or 17th C. and involves discovering a discord on what kind of years to count forwards from up to Christ’s birth.

Ab Urbe Condita is available, but as our religion holds the Universe and cities existed before Rome was founded, it doesn’t get you very far.

Anno Mundi is also available, but Latin Christians and Byzantine ones had been differring on that one, due to using different manuscripts of LXX, and Ussher added another layer of disunity on that one.

"Did people who lived in the BC days, actually count their years backward?”

Obviously not, as said.

“Who thought of this convention?”

Dionysus exiguus started the AD forwards part. He started it in 525 AD, meaning he could at least theoretically have been wrong a year or two or four.

What about BC?

"The Venerable Bede, who was the first writer to identify a year as before Christ, used the Latin ante incarnationis dominicae tempus (before the time of the incarnation of the Lord) in his Historia ecclesiastica gentis Anglorum (I.2) in 731."

Ante Christum natum - Wikipedia

However, I don't think it became popular from him on.

Found the populariser:

"In 1627, the French Jesuit theologian Denis Pétau (Dionysius Petavius in Latin), with his work De doctrina temporum, popularized the usage ante Christum (Latin for "Before Christ") to mark years prior to AD."

Anno Domini - Wikipedia

“Sure, it's supposed to revolve around the birth of Christ but it didn't exactly and even then, it's confusing as hell.”

Even so, for years prior to founding of Rome, with competing Anno Mundi for Christ born 5500 or 5199 Anno Mundi, it was a boon, since the chronology of last centuries and millennium BC is batter documented than the exact details of chronology in first millennium AM.

“I dunno, why not just have the birthplace of civilization like Mesopotamia or something be year 0 and then move forward from there. So 2014 today would be year 5000 something or 6000 something. Doesn't that make more sense?"

Not really, first, since there are Christians who would, if so, prefer Anno Mundi, second, the Sumerians actually did not have an era, but counted each new ruler as a new era.

Update

since Julian calendar came a bit before AD, here is an answering taking into account pre-Julian both Roman and non-Roman calendars.

Q III

How many months are in a leap year?
https://www.quora.com/How-many-months-are-in-a-leap-year/answer/Hans-Georg-Lundahl

Hans-Georg Lundahl

Self Employed at Writer and Composer

Answered just now

How many months there are in a leap year depends on the calendar type.

Julian and Gregorian calendars are purely solar, months have conventional lengths, the intercalation is one day, and the number of months is identical.

Hebrew and old Athenian (as well as pre-Julian Roman) ones are more or less Luni-Solar, months are Lunar and now and then the year gets thirteen lunar (?) months instead of twelve, because twelve lunar months is clearly shorter than a solar year.

With pre-Julian Roman calendar, I am not sure about the thirteen lunar months for leap years, since Mercedonius was intercalated into February, not added after or before, February cannot have been one and Mercedonius another lunar month. However, the two calendar months beginning and ending as February and having Mercedonius inbetween, can have been together two lunar months.

Unless of course this is a misunderstanding, so that “ante diem sextum kalendis martiis” would back then have been certain years a day in February and other years a day in Mercedonius, or simply left indifferent, as the reference is to the following kalends of March, that usually being considered as the first of the month and now certainly means “first of”.

Let us also note, the Egyptian calendar on which Julius Caesar based his calendar reform was a wandering year:

The ancient Egyptian calendar was a solar calendar with a 365-day year. The year consisted of three seasons of 120 days each, plus an intercalary month of 5 epagomenal days treated as outside of the year proper. Each season was divided into four months of 30 days. These twelve months were initially numbered within each season but came to also be known by the names of their principal festivals. Each month was divided into three 10-day periods known as decans or decades. It has been suggested that during the Nineteenth Dynasty and the Twentieth Dynasty the last two days of each decan were usually treated as a kind of weekend for the royal craftsmen, with royal artisans free from work.

Because this calendrical year was nearly a quarter of a day shorter than the solar year, the Egyptian calendar lost about one day every four years relative to the Gregorian calendar. It is therefore sometimes referred to as the wandering year (Latin: annus vagus), as its months rotated about one day through the solar year every 4 years. Ptolemy III's Canopus Decree attempted to correct this through the introduction of a sixth epagomenal day every four years but the proposal was resisted by the Egyptian priests and people and abandoned until the establishment of the Alexandrian or Coptic calendar by Augustus. The introduction of a leap day to the Egyptian calendar made it equivalent to the reformed Julian calendar, although it continues to diverge from the Gregorian calendar at the turn of most centuries.

Egyptian calendar - Wikipedia
https://en.wikipedia.org/wiki/Egyptian_calendar