 They are regarded as the partial ancestors of the Western Turks – the present-day inhabitants of the Republic of Azerbaijan (historically known as Shirvan and Arran), Azerbaijan (historic Azerbaijan, also known as "Iranian Azerbaijan"), Turkmenistan, and Turkey.The "Great Seljuqs" were heads of the family; in theory their authority extended over all the other Seljuq lines, although in practice this often was not the case.Turkish custom called for the senior member of the family to be the Great Seljuq, although usually the position was associated with the ruler of western Persia.