|Centuries:||2nd century BH – 1st century BH – 1st century|
|Years:||4 BH 3 BH 2 BH – 1 BH – 1 AH 2 AH 3 AH|
Year 1 BH was the 13th year after the year of Bi'tha (beginning of the prophet's mission). Year 1 BH started on Monday, July 27, 621 CE and ended on Thursday, July 15, 622 CE in the Julian calendar.
In this year the severity of Quraysh against Muslims became harsher. So the Prophet (s) told Muslims to go to their supporter brothers (Ansar) in Yathrib and the emigration of Muslims began from Dhu al-Hijja 1 BH/July 622 CE.
- Dhu al-Hijja – By the permission of the prophet (s), Muslims began to migrate from Mecca and in less than 3 months, most of the companions of the Prophet (s) emigrated to Yathrib (July 622 CE).