|''caliph'' Abu Bakr al-Baghdadi|
"The Shura (council) of the Islamic State met and discussed this issue... (and) the Islamic State decided to establish an Islamic caliphate and to designate a caliph for the state of the Muslims," said Adnani.
The spokesman added that the caliphate, which is named the Islamic State, will extend from Aleppo in northern Syria to Diyala in Iraq.
On June 10 ISIS gained control of Mosul, the capital of Iraq’s Nineveh Province, which was followed by the fall of Tikrit, located 140 kilometers (87 miles) northwest of Baghdad.
Over the past days, Iraqi armed forces have been engaged in fierce clashes with the militants, who have threatened to take their acts of violence to other Iraqi cities, including the capital, Baghdad. However, the ISIS’s advance has been slowed down as Iraqi military and volunteer forces have begun engaging them on several fronts.
Declaring a “caliphate” is a move that has huge ideological significance. Defined as meaning “the government under a caliph”, it means ISIS, now simply The Islamic State (IS), has declared its leader Abu Bakr al-Baghdadi as the spiritual leader of all Islam. The word “caliph” comes from the Arabic khalifa, meaning “successor”. Its use means the IS claims Baghdadi as the only legitimate successor to the Prophet Mohammed.
In the past the role of caliph has largely been symbolic,leaving the day-to-day running of government down to the devolved powers of local rulers.The last widely-acknowledged caliphate was under the Ottoman Empire, which used the symbolic power of its caliph to rule across vast reaches of the Arabic world. The caliphate in this sense ended with the establishment of the Turkish Republic in 1923.