A patriarchate is the office or jurisdiction of an ecclesiastical patriarch. A patriarch, as the term is used here, is either,
The five patriarchs of the Pentarchy sat in Rome, Constantinople (now Istanbul), Alexandria, Antioch, and Jerusalem. The East-West Schism of 1054 split the Latin-speaking see of Rome from the four Greek-speaking patriarchates, forming distinct Roman Catholic and Eastern Orthodox Churches. The Eastern Orthodox Patriarch of Antioch moved to Damascus in the 13th century, during the reign of the Egyptian Mamelukes, conquerors of Syria. In Damascus a Christian community had flourished since apostolic times (Acts 9). However, the patriarchate is still called the Patriarchate of Antioch. Damascus is the seat also of the Syrian Catholic and the Melkite Catholic Patriarchs of Antioch, while the Maronite Catholic of Antioch lives in Bkerké, Lebanon.
The four early Orthodox (Greek) patriarchates of the East, Constantinople, Alexandria, Antioch and Jerusalem, along with their Latin Catholic counterpart in the West, Rome, are distinguished as "senior" (Greek: πρεσβυγενή, presbygenē, "senior-born") or "ancient" (παλαίφατα, palèphata, "of ancient fame") and are among the apostolic sees, having had one of the Apostles or Evangelists as their first bishop: Andrew, Mark, Peter, James, and Peter again, respectively.
In the Roman Catholic Church, some patriarchal titles are purely honorary, without an actual residential see, and hence termed Titular Patriarch(ate)s, either vested in another (residential) patriarchal see or in the Pope's gift.
A patriarchate has "legal personality" in some legal jurisdictions, that means it is treated as a corporation. For example, the Orthodox Patriarchate of Jerusalem filed a lawsuit in New York, decided in 1999, against Christie's Auction House, disputing the ownership of the Archimedes Palimpsest.
The head of the Czechoslovak Hussite Church is also called a Patriarch.