The Initiation of the Hijrah Calendar

The Hijrah calendar is regarded as a development that had a major cultural impact. The first one to introduce this was ‘Umar Ibn Al-Khattaab. There are several reports which speak of the reason for that. 

It was narrated that Maymoon Ibn Mahraam said:

“A document that was dated in Sha’baan came to ‘Umar, and he said, “Is this Sha’baan of last year, or Sha’baan of the coming year, or the Sha’baan we are in now?”

Then he gathered the Companions of the Messenger of Allah (saws) and said to them, “Set up something for the people that they can refer to.”

Someone suggested using the Byzantine (Roman) calendar, but it was pointed out that it was too long as they dated it from the time of Dhul-Qarnayn. Someone else suggested using the Persian calendar, but they said that every time a new king came along, he abolished what had gone before. Then they agreed to look at how long the Messenger of Allah (saws) had stayed in Madinah, and they found that he had stayed there for ten years, so they based their calendar on the Hijrah of the Messenger of Allah (saws).”

[Mahd As-Sawaab, 1/316; Ibn Al-Jawzee, p.69] 

It was narrated that ‘Uthmaan Ibn ‘Ubaydillaah said that he heard Sa’eed Ibn Al-Musayyib say:

” ‘Umar Ibn Al-Khattaab gathered the Muhaajiroon and Ansaar together and said, “From when should we date our history?”

‘Ali Ibn Abi Taalib said to him, “From the time when the Prophet (saws) came out of the land of shirk (i.e. from the day he (saws) migrated).”

So ‘Umar Ibn Al-Khattaab adopted that date for the beginning of the calendar.”

And it was narrated that Sa’eed Ibn Al-Musayyib said:

“The first one to establish the calendar was ‘Umar Ibn Al-Khattaab, two and a half years into his caliphate. He reached a decision in consultation with ‘Ali Ibn Abi Taalib.

[Taareekh Al-Islaam, by Adh-Dhahabi, p.163]

Abu Az-Zanaad said:

” ‘Umar consukted others concerning the calendar, and they agreed upon the Hijrah.”

[mahd As-Sawaab, 1/317] 

Ibn Hajr narrated the reasons why they chose Muharram for the beginning of the calendar and not Rabi’ Al-Awwal, the month in which the Prophet (saws) actually migrated: the Companions who advised ‘Umar suggested four events that could be used as the starting point for the calendar: 
(1) the Prophet’s (saws) birth, 
(2) the beginning of his mission, 
(3) his Hijrah, 
(4) his death. 
But they found that there was some dispute as to the year of his birth, and the beginning of his mission, and they also abandoned the idea of dating the calendar from his death because that would provoke grief and sorrow in the Muslims. 

So there was no other option left but the Hijrah. 

And they put it back from Rabi’ Al-Awwal to Muharram because the initial resolve to migrate came in Muharram. 

The second pledge of Al-‘Aqabah, which was the precursor to the Hijrah, had taken place in Dhul-Hijjah; the first new month to begin after that pledge and resolve to migrate was Muharram. So it was apt that this month should be chosen for the appropriate event to be regarded as the beginning of the calendar. 
Then Ibn Hajr said:

“This is the most appropriate event to be regarded as the beginning, which took place in Muharram.”

[Fath Al-Baari, 7/268; Al-Khilaafah Ar-Raashidah by Yahya Al-Yahya, p.286]

[Taken from ‘Umar Ibn Al-Khattab, His Life And Times, By Shk Dr. ‘Ali Muhammad As-Sallaabi, 1/225-227]