old; in the year that Persian king, Dari-Ardashir opened the city Hatra, and in the year Shapur Shah, his son, put the largest crown in the month Famuthi, on the month day (8th day of Farmuthi), my god, who is the most blessed, made me proud by his generosity, summoned me by his favor...It can be deduced by calculating the Egyptian month and year that Shapur's coronation as his father's royal partner occurred on April 12, 240 (the first day of the Babylonian month Nisan in the year 551). Ardashir and Shapur's simultaneous reign lasted apparently until early 242. Therefor, it can be said that Shapur was probably crowned twice; once as a royal partner in 240 and later in 243 as lonely reign; however it is more probable that he was crowned only once in 240. Timeline of life According to three dates that are achieved from Shapur's inscription on a column in Bishapur, the period between 205 and 206 appears as the beginning of an era in Sasanian history; it is written in the first lines of the mentioned inscription:1- Farvardin 58, 2- Azar Ardashir 40, 3- Azar Shapur from royal Azars 24Therefor, history is designated with "three eras" in the inscription; "Azar Ardashir 40" means the 40th year in Ardashir's era and "Azar Shapur 24" means the 24th year in Shapur's era. 58 shows an era that has remained unknown. It has been deduced from the allusion that one of the mentioned events (overthrowing the local shah of Istakhr by Papak or announcing independence from the Parthians) has happened between the years 205 and 206; since the year is implied as "the year of the beginning of an era". The assumption that "the period between the years 205 and 206" is related to Papak's rebellion is very probable since "the period between the years 205 and 206" was never a basis in any of the future achieved histories from the Sasanians and usually every Sasanian emperor either based the calendar on the year of "his ascension" or based it on the Seleucid calendar that began with 312 B.C. R. Ghirshman believes that the year 58 shows the beginning of the domination of the Sasanian dynasty over the Iranian lands. Besides, the date of altering the Persian coins along with which the names of previous governors were replaced with the Sasanian dynasty can be accepted to be 205–206.