http://askaquestionto.us/tag/umarAsk your questions, find authentic answersWhen has the Hijri Calendar been started to be used? When has the Hijri Calendar been accepted as the Islamic Calendar?http://askaquestionto.us/question-answer/hijra/when-has-the-hijri-calendar-been-accepted-as-the-islamic-calendarHijraTue, 15 Mar 2011 23:18:00 GMT