In theory, a caliphate is more than just a country that happens to be officially Muslim; it is supposed to encompass every Muslim on earth. The present-day Abu Bakr al-Baghdadi, Iraqi jihadist leader who declared himself the new caliph, in declaring himself a caliph and his terrorist mini-state a caliphate, is communicating that he believes he is fighting on behalf of all Muslims worldwide (he does not count Shia Muslims in this, only Sunnis) and that he is the representative of God on earth. He is also sort of suggesting a desire to continue ISIS's advance until he has conquered all Muslim-majority lands, which is an aspiration that's hinted at frequently in jihadist maps of a unified Islamic empire: