Maundy Thursday April 22 inclusive, but these dates fall on different days depending on whether the Gregorian calendar or Julian calendar is used liturgically. Eastern churches generally use the Julian calendar and celebrate this feast throughout the 21st century between April 1 and May 5 in the more commonly used Gregorian calendar. The liturgy held on the evening of Maundy Thursday initiates the Easter Triduum, the period which commemorates the passion, death, and resurrection of Jesus; this period includes Good Friday and Holy Saturday, and ends on the evening of Easter. The Mass of the Lord's Supper or service of worship is
Zoroastrian calendar ... after which the Elamite tablets cease." No dated West-Iranian documents from this period survive, but the fact that the Zoroastrian calendar was created at this time can be inferred from its use in a number of far-flung lands which had formerly been parts of the Achaemenid Empire. The oldest (though not dateable) testimony for the existence of the day dedications comes from "Yasna" 16, a section of the Yasna liturgy that is – for the most part – a veneration to the 30 divinities with day-name dedications. The "Siroza" – a two-part Avesta text with individual dedications to the