Calendar Systems. Four countries utilize an altered version of the gregorian calendar (with eras different from anno domini): Calendar apps make it easy to manage and organize your schedule, appointments, events, and tasks on the go.
You may click on the “ [toc]” links to return to the calendar systems table of contents. The persian calendar has been called “one of the world’s most accurate calendar systems.” like the islamic calendar, it dates back to muhammad’s hegira in 622 ce, but it is otherwise quite.