The use of the solar calendar was introduced in 1889 by King Chulalongkorn (Rama V), replacing the lunar calendar in official contexts. The beginning of the year was originally marked as April 1st, however this was changed to January 1st in 1941. The days and months now correspond exactly to the Gregorian calendar. The years follow the Buddhist Era, introduced in 1913 to replace the Rattanakosin Era, which in turn replaced the Chula Sakarat in 1889. The reckoning of the Buddhist Era in Thailand is 543 years ahead of the Common Era (Anno Domini), so the year  CE corresponds to B.E. .