In this calendar, each year had 12 months of 30 days. Each month had a name. The week was not important but each day of the month had also a name. All the names were of Emšâspandân, angles, or Izadân, gods. These names were repeated every thirty days. When the name of the day and month were the same, Zoroastrians would celebrate that day. For instance, the fourth month of the year is Tir, and the 13th day of each month is also named Tir. So, the 13th day of the 4th month of a year, July 4th, is called Tirgân in the Zoroastrian calendar (Razi, 2001: 127-128). Tirgân is still celebrated in different parts of Iran among people with various religious beliefs.