The first day of the Islamic year is called “Awal Tahun Hijrah,” in reference to the first day of the Islamic “Hijrah” Calendar. The Islamic Calendar and dating system begins with the “hijrah” (flight) of Muhammad from Mecca to Medina in C.E. 622.
In Brunei, both Western New Year’s Day on 1 January and Islamic New Year’s Day on 1 Muharram are publicly recognised holidays. This makes sense since Brunei is predominantly Muslim and yet is interconnected to the rest of the world that largely follows the Gregorian Calendar.