Beylerbey or
Beylerbeyi (; "
Bey of Beys", meaning "the Commander of Commanders" or "the Lord of Lords"; originally
Beglerbeg[i] in older
Turkic) was a high rank in the western Islamic world in the late
Middle Ages and
early modern period, from the
Seljuks of Rum and the
Ilkhanids to
Safavid Persia and the
Ottoman Empire. Initially designating a
commander-in-chief, it eventually came to be held by senior provincial governors. In Ottoman usage, where the rank survived the longest, it designated the governors-general of some of the largest and most important provinces, although in later centuries it became devalued into a mere honorific title. Its equivalents in
Arabic were
amir al-umara, and in Persian,
mir-i miran.