Old Calendarists are small separatist communities formed in Greece, Romania, Cyprus, Bulgaria and elsewhere after the adoption of the Revised Julian liturgical calendar (which is essentially the Gregorian calendar combined with the Orthodox Paschalion) in the early 20th century. Citing the 16th century anathemas against the Gregorian calendar issued by three endemousa (or "Patriarchal") synods in Constantinople, as well as various condemnations by multiple local synods, they have become some of the most vocal critics not only of the new liturgical calendar, but of ecumenism in general, which is seen as the ultimate cause of the calendar revision.