#SaudiArabia used the #LunarHijriCalendar for all official purposes until the 1950s. At some point, it was decided to switch to a #SolarCalendar to reduce the frequency of monthly salary payments, thus saving the government money.

Arabia adopted the Gregorian calendar, which is used throughout the world, partly because it would make #commerce easier. #OmarKhayyam had invented better calendars, but money talks and Arabians are apparently OK with Christians than the wrong type of Muslims.