永えい祚そえいそMeanings1nounEiso era (989.8.8-990.11.7)A specific Japanese era name (年号) used from August 8, 989 to November 7, 990 in the Gregorian calendar.永えい祚そ元がん年ねんは西せい暦れき989年ねんにあたる。The first year of the Eiso era corresponds to 989 CE.