-

The solar Jalali chronology, was established during the age of the Saljughi Sultan Jalal aI-din Malekshah. (465-485 A.H.). The present Iranian solar
calendar is based on the same chronology. The starting point of this calendar


was on Friday , the ninth of Ramadan, 471 A.H. corresponding to March the fifteenth, 1079 A.D, and Farvardin the first, 458 A.H(according to solar
calendar).
In Jalali chronolgy, the name of the months is the same as what was in the
ancient Iranian calender. One of the characteristics of this chronology, which has increased its exactness, is applying two kinds of leaps. In one style, each
four-year period will have a leap year, and in the other each 29 or 33-year period will have a leap known as khumasi.
Concerning the exactness of Jalali chronology various and detailed researches have been done up to now, and the majority of experts in
chronology have unanimously approved the high exactness of it in comparison to the other calendars.
the present article attempts to give berief information concerning the current calendars of ancient Iran and the characteristics of Jalali chronology.