When Did the Hijri Calendar Start, and Who Introduced It?

Why Did the Hijri Calendar Need a Starting Point?

The Arabs of central Arabia already tracked twelve lunar months with names, including Muharram and Ramadan. What they lacked was a counted year. Years were remembered by events, so no number told one year from the next.

That was fine for a village. It became a problem for a state that was growing fast and sending written orders over long distances.

Our knowledge of pre-Islamic central Arabia is limited. Most details come from writers of the Abbasid period, who wrote centuries later. Treat many early claims as reported tradition, not as eyewitness record.

Who Introduced the Hijri Calendar?

The traditional answer is Umar ibn al-Khattab, the second caliph, who ruled from 634 to 644 CE. Sources place the decision about 17 years after the Hijra, which is about 638 CE.

Wikipedia says Umar acted after a complaint from Abu Musa al-Ash’ari, a Basra official. Umar’s letters carried no year. Recipients could not tell which instruction was the latest.

Another account has Abu Musa writing about a document dated only “Sha’ban”. He could not tell which Sha’ban was meant. Both versions describe the same need for a numbered year.

How Was the Hijra Chosen as the Epoch?

Accounts say Umar asked a gathering of people how years should be counted. Several starting points were put forward.

• The start of the Prophet’s mission, per an account cited by Ibn Hajar.
• The Hijra, the move from Mecca to Medina.
• The Prophet’s birth or death, which some later retellings add.

In the account Ibn Hajar quotes, Umar chose the Hijra and said it separated truth from falsehood. Other modern retellings add a practical reason: the date of the move was well known.

Notice what the era does not count. It does not count from the day of the Hijra itself. It counts the whole year in which the move happened, as year one.

The abbreviation AH stands for Anno Hegirae, Latin for the year of the Hijra. Dates are written the same way as CE years, such as 17 AH.

Why Does the Year Begin in Muharram?

The Hijra itself did not happen in Muharram. Wikipedia’s article on the Hijri year puts the arrival around 8 Rabi al-Awwal, about two months into that year. Muharram was chosen as the start of the count, not as the date of the event.

The sources give several reasons for Muharram.

• It was already the first month in Arab custom, a point Uthman is credited with raising.
• It follows the pilgrimage season, when pilgrims return home, per Ibn Hajar’s account.
• Ibn Kathir adds that the firm intention to emigrate formed in that month.

Some people proposed Ramadan instead. According to the same narration, Umar preferred Muharram.

The name Muharram (محرم) has an Abjad value of 288, while the word Hijra (هجرة) comes to 213. These are only arithmetic and have no bearing on the history. See the Abjad value calculator if you want to try other words.

How Did Earlier Arabian Practice Compare?

Before the era, the Arabs distinguished sacred months in which fighting was set aside. These were Rajab, Dhu al-Qa’da, Dhu al-Hijja and Muharram. The practice of nasi’, a postponement, was tied to these months.

Scholars disagree about what nasi’ did.

The Purely Lunar View

Ibn Hisham, Ibn Manzur and the Quranic commentators held that the calendar was purely lunar. On this view, nasi’ only moved the sacred months around. The year itself stayed lunar.

The Lunisolar View

Abu Ma’shar al-Balkhi was first to propose that the calendar became lunisolar about 200 years before the Hijra. Al-Biruni and al-Mas’udi agreed. On this view, nasi’ meant adding an extra month, called intercalation.

The proposed patterns differ too. One is seven extra months in nineteen years, and another is nine in twenty-four. Scholars have no consensus.

All accounts agree on the next step. The Quran, in verses 9:36 and 9:37, prohibits nasi’. Tradition places this in the tenth year of the Hijra.

The result is a fixed year of twelve lunar months with no extra month. A year therefore has 354 or 355 days. That is about 11 days shorter than a solar year, so it drifts through the seasons.

What Date Did the Hijri Calendar Begin?

Two epoch dates are in use. They differ by exactly one day, and both are in the Julian calendar, which was the calendar of 622 CE.

The 16 July date was set by medieval Muslim astronomers. They projected their tabular calendar backward, and al-Biruni cited it in the year 1000 CE.

NASA’s calendar notes call Thursday, 15 July the astronomical epoch and Friday, 16 July the civil one. In both, the Islamic day starts at sunset on the evening before.

The same date in the proleptic Gregorian calendar is 19 July 622. See the page on Hijri calendar systems for how tabular, astronomical and sighting-based calendars differ.

How Do the Dates Add Up from Year One to Year 17?

The tabular calendar repeats a 30-year cycle. It has 19 common years of 354 days and 11 leap years of 355 days. The leap years are the 2nd, 5th, 7th, 10th, 13th, 16th, 18th, 21st, 24th, 26th and 29th.

1. Count the full years between the starts: 17 − 1 = 16.
2. Multiply by 354: 16 × 354 = 5,664 days.
3. Add the leap days in years 1 to 16: years 2, 5, 7, 10, 13 and 16 give 6 days.
4. Total: 5,664 + 6 = 5,670 days.

Adding 5,670 days to the epoch, Julian day 1948440, gives 1954110. That is 23 January 638 CE in the Julian calendar, the start of 17 AH in the tabular reckoning.

The 30-year cycle holds 10,631 days, so the average year is 354.37 days. That is about 10.9 days shorter than a 365.25-day solar year.

This is why Hijri dates slide earlier in the Gregorian year. The Hijri to Gregorian formula page shows the full method.

What Is Known About the First Years of Use?

Wikipedia notes that the earliest surviving document with a Hijri and a Coptic date is a papyrus from AH 22. It also says Cook and Crone cite a coin from AH 17.

The article also records a dissenting view. The scholar Shamsi argued in 1984 that the calendar was never intercalated at all.

On that view, 1 Muharram of the first year was an ordinary day. The move from Quba’ to Medina then fell on 26 Rabi’ I of the older calendar.

Early dates are reconstructions. As a check, the tabular date for 9 Dhu al-Hijja, 10 AH falls on 7 March 632 (Julian).

Wikipedia gives 6 March for that day. A one-day gap between tabular and observed reckoning is normal.

The month names, their lengths and their order are covered on the Hijri months page. The wider series starts at the Hijri calendar guide.

Why Does This History Matter for Ilm-ul-Adad?

Most Urdu and Persian chronograms give a Hijri year. A poet who hid a year in a phrase usually meant that era. So you must know the era before you read the date.

The chronogram guide and the tarikh goi page explain the practice. The history section places it among other Abjad traditions.

Sources and Further Reading

• Islamic calendar, Wikipedia. Umar’s introduction, nasi’, the epoch date and the dissenting views.
• Hijri year, Wikipedia. The epoch, Muharram as the first month and the date of the arrival in Medina.
• Tabular Islamic calendar, Wikipedia. The 30-year cycle and the leap years.
• Calendars and their History, NASA Eclipse Web Site. The astronomical and civil Hijra epochs.
• Calendar Converter, John Walker, Fourmilab. The epoch as Julian day 1948439.5 and the 30-year cycle.
• A350539, OEIS. The epoch as JDN 1948440 and the 15 July alternative.
• The year the Hijri calendar was introduced, IslamWeb. Ibn Hajar’s quotation of the narration from Abu Nu’aym and al-Hakim.
• The story of the Hijri calendar, Safeerat Al Islam. Ibn Kathir’s statement of 16 or 17 AH, and the reasons for Muharram.
• How and Why did the Hijiri Calendar Begin?, Al Ain University library. The retelling that mentions birth and death as proposals.
• Abjad values come from this site’s tested engine. See the methodology.

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