An emperor's era name or reign name was chosen at the beginning of his reign to reflect the political concerns of the court at the time. A new era name became effective on the first day of the Chinese New Year after that emperor's accession, which fell between 21 January and 20 February (inclusively) of the Gregorian calendar. Even if an emperor died in the middle of the year, his era name was used for the rest of that year before the next era officially began.