the article states at iranian calendar modern era from that in the shah decreed that solar hejri year became the imperial year thus the first imperial year was the year that cyrus the great acceded to the throne in bc not his birth year many years earlier this would mean that during gregorian year the imperial year would have begun if the solar hejri year had not been reinstated in your year would imply a first imperial year years after cyrus began his reign after he had conquered many nations inducing their kings to bring him gifts this would be even more arbitrary then the beginning of his reign which is a well known year his birth year is assigned to be two different years either bc or bc regarding nowruz in achaemenid times the official year began at nowruz at the vernal equinox but popular usage placed nowruz at the summer solstice in sasanid persia gifts were presented to the king at nowruz these two dates for nowruz persisted into the islamic period see nawruz in the encyclopaedia of islam