Choose the day of arrival at Medina as starting date for Muslim calendar

The Prophet Muhammad's companions decided to use his arrival in Medina as a starting point for their calendar, rather than when he was first sent as a prophet or when he passed away. This is because they wanted to commemorate and celebrate this momentous occasion in which Muhammad arrived in Medina and began to spread Islam. This event marked a new era in Islamic history and it is important that Muslims remember this event by using it as a reference point for their calendar. It also serves to remind us of how far we have come since then and how much progress has been made since then.