The Bulgarian Orthodox Church (), legally the Patriarchate of Bulgaria (), is an autocephalous Eastern Orthodox jurisdiction based in Bulgaria. It is the oldest Slavic Orthodox church, with some 6 million members in Bulgaria and between 1.5 and 2 million members in a number of other European countries, Asia, the Americas, Australia, and New Zealand. It was recognized as autocephalous in 1945 by the Ecumenical Patriarchate of Constantinople. History Early Christianity The Bulgarian Orthodox Church has its origin in the flourishing Christian communities and churches set up in the Balkans as early as the first centuries of the Christian era. Christianity was brought to the Balkans by the apostles Paul and Andrew in the 1st century AD, when the first organised Christian communities were formed. By the beginning of the 4th century, Christianity had become the dominant religion in the region. Towns such as Serdica (Sofia), Philipopolis (Plovdiv), Odessus (Varna), Dorostorum (Silistra) and Adrianople (Edirne) were significant centres of Christianity in the Roman Empire. The Monastery of Saint Athanasius, the first Christian monastery in Europe, was founded in Thrace in 344 by Athanasius near modern-day Chirpan, Bulgaria, following the Council of Serdica and the Edict of Serdica. The barbarian raids and incursions in the 4th and the 5th centuries, and the settlement of Slavs and Bulgars in the 6th and the 7th centuries, wrought considerable damage to the ecclesiastical organisation of the Christian Church in the Bulgarian lands, yet did not destroy it. Kubrat and Organa were both baptized together in Constantinople and Christianity started to pave its way from the surviving Christian communities to the surrounding Bulgar-Slavic mass. By the middle of the 9th century, the majority of the Bulgarian Slavs, especially those living in Thrace and Macedonia, were Christianized. The process of conversion also enjoyed some success among the Bulgar nobility. However, it was not until the official adoption of Christianity by Khan Boris I in 865 that an independent Bulgarian ecclesiastical entity was established. Establishment Boris I believed that cultural advancement and the sovereignty and prestige of a Christian Bulgaria could be achieved through an enlightened clergy governed by an autocephalous church. To this end, he manoeuvred between the Patriarch of Constantinople and the Roman Pope for a period of five years until in 870 AD, the Fourth Council of Constantinople granted the Bulgarians an autonomous Bulgarian archbishopric. The archbishopric had its seat in the Bulgarian capital