The initial organization dates back to the Ottoman beginnings as a
Seljuk vassal state (
Uç Beyligi) in central
Anatolia. The Ottoman Empire over the years became an amalgamation of pre-existing
polities, the
Anatolian beyliks, brought under the sway of the ruling
House of Osman. This extension was based on an already established administrative structure of the
Seljuk system in which the hereditary rulers of these territories were known as
beys. These beys (local leadership), which were not eliminated, continued to rule under the
suzerainty of the Ottoman
sultans. The term bey came to be applied not only to these former rulers but also to new governors appointed where the local leadership had been eliminated. The Ottoman Empire was, at first, subdivided into the sovereign's
sanjak and other sanjaks entrusted to the
Ottoman sultan's sons. Sanjaks were governed by
sanjakbeys, military governors who received a flag or standard – a "
sanjak" (the literal meaning) – from the sultan. As the Empire expanded into
Europe, the need for an intermediate level of administration arose and, under the rule of
Murad I (r. 1359–1389), a
beylerbey ("bey of beys") or governor-general was appointed to oversee
Rumelia, the European part of the empire. At the end of the 14th century, a
beylerbeylik was also established for
Anatolia, with his capital at
Kütahya. He was always considered inferior in rank to the
beylerbey of Rumelia, since large areas nominally under his control were given to the ruler's sons. Following the establishment of
beylerbeyliks,
sanjaks became second-order administrative divisions, although they continued to be of the first order in certain circumstances such as newly conquered areas that had yet to be assigned a
beylerbey. In addition to their duties as governors-general,
beylerbeys were the commanders of all troops in their province. Following the conquests between 1362 and 1400 of
Murad I and his son
Bayezid I, a need arose for the formal organisation of Ottoman territory. ==Administrative hierarchy==