Situated in the region of Bithynia in the north of Asia Minor, Osman's principality found itself particularly well placed to launch attacks on the vulnerable Byzantine Empire, which his descendants would eventually go on to conquer.

[12] Turkish historian Halil İnalcık argued that the hypotheses that Osman was in fact named Ataman (per George Pachymeres), and that he came from the Desth-i Qipchaq north of the Black Sea, are both remote possibilities.

[16] Other sources claim that the Kayı clan moved to Anatolia two centuries earlier than the previously mentioned date, alongside the Seljuks, when they left Transoxiana to Khurasan around 1040 to reside near the city of Merv.

Thus, he started raiding the Byzantine possessions in the name of the Sultan successfully conquering several towns and villages, and slowly expanding his dominion during the half of the century he spent as a Seljuk governor.

[26] The Ottoman historian Kemalpaşazâde mentioned that Osman was Ertuğrul's youngest son and that he was raised in the traditional nomadic Turkic ways: he learned wrestling, swordsmanship, horse riding, arrow shooting, and falconry, from an early age.

[26] The exact date of Osman's birth is unknown, and very little is known about his early life and origins due to the scarcity of sources and the many myths and legends which came to be told about him by the Ottomans in later centuries.

[2] According to Ottoman tradition, Osman's father Ertuğrul led the Turkic Kayı tribe west from Central Asia into Anatolia, fleeing the Mongol onslaught.

[36] Commenting on these actions, some historians argue that Osman's strategy of increasing his territories at the expense of the Byzantines was due to his intention to avoid conflicts with his more powerful Turkic neighbours.

Add to that, its proximity to the Silk Road linking Byzantine lands in the west to areas controlled by the Mongols in the east, gave it prominent strategic and economic characteristics.

Also, the Osmanic beylik was the only Islamic base facing the yet unconquered Byzantine regions, which made it a magnet to many Turkomen farmers, warriors, and Dervishes fleeing the Mongols, and aspiring to conquer new lands for economic and religious reasons.

[39]The dream became an important foundational myth for the empire, imbuing the House of Osman with God-given authority over the earth and providing its fifteenth-century audience with an explanation for Ottoman success.

[42] Once Bābā Eliyās died, both Ḥājī Baktāš Walī and Sheikh Edebali became among his 60 successors, and grandmasters of the Ahyan Rûm brotherhood of warriors and farmers, who enjoyed great influence among the people.

Osman's alliances transcended tribal, ethnic, and religious lines, and he may have followed his instinct and the requirements of his political aspirations, not mistaking the future results of the family connections he created and secured for his son after him.

[48] As for the hierarchy of name delivering in khuṭbah, Imams used to pray for the guidance of the: Abbasid caliph in Egypt first, the Mongol Ilkhan in Tabriz, Seljuk Sultan in Konya, and finally the local Bey or Emir.

Osman made his new city a staging base of his military campaigns against the Byzantines, and ordered that his name be delivered at the Friday khuṭbah, which was the first manifestation of his sovereignty and authority.

That is because he considered the relationship with Bilecik to have been built on trust and good faith, as demonstrated by the aforementioned custom of his clan leaving their belongings in this fortress whenever they moved between grazing areas.

During that time, the Byzantine Empire was preoccupied with ongoing clashes with its powerful enemies in Anatolia, such as the Germiyanids and the coastal beyliks, not to mention suppressing unrest and discord in Constantinople and the Balkans.

This prompted the Mongol Ilkhan Mahmud Ghazan to call upon Kayqubad to appear before him, and once the latter did in 1302, he was executed and replaced with his predecessor Ghiyāth ad-Dīn Mas'ūd bin Kaykāwūs to keep the peace in Anatolia.

[60] In all cases, Kaykāwūs's rule was short-lived, lasting between 4 and 6 years at most, and when he died in 1308 CE, the Seljuk Sultanate of Rûm was no more to be mentioned in the historical records,[69] giving the way for the Turkoman beyliks to emerge as independent states.

It is likely that Kayqubad's and Kaykāwūs's deaths led to the Sultanate of Rûm falling into chaos, and prompted many of its regular soldiers to join the armies of local Emirs, including Osman.

[70] Soon after Osman secured his independence and established control over all fortresses he conquered, he sent messages to all remaining Byzantine tekfurs in Anatolia asking them to choose between accepting Islam, Ottoman sovereignty and paying jizyah, or war.

[75][76][77] To counter the threat to Nicomedia, Michael's father, Andronikos II, sent a Byzantine force of some 2,000 men (half of whom were recently hired Alan mercenaries), under the megas hetaireiarches, Giorgios Mouzalon, to cross the Bosporus and relieve the city.

Another example is the Ḥajjian Rûm's (pilgrims of [the land of] the Romans), a brotherhood of Muslim clergy concerned with teaching local villagers and recent converts the basics and different aspects of Islam, and had a side objective of assisting the Mujahideen in combat.

The Emperor arranged the wedding of Roger de Flor to his niece, the 15-year-old princess Maria Asanina, daughter of the Tsar of Bulgaria Ivan Asen III and Irene Palaiologina.

Afterward, they resolved to attack the maritime provinces of the Ottomans and moved to the town of Philadelphia which was besieged by Yakup I of Germiyan, who suffered a defeat at the hands of the Catalans and was forced to lift his siege and retreat.

The reason for that was that the local population of Magnesia beheaded the Catalan garrison and stole its treasure, which infuriated Roger de Flor and made him march towards that city intending on revenge.

[89] Soon after that Osman started sending more campaigns against the remaining Byzantine cities conquering several fortresses including Lefke, Akhisar, Koçhisar, Yenicehisar, Marmaracık, and Köprühisar.

Soon after that, Osman started suffering from Gout, and couldn't accompany his men in any more campaigns or witness the Siege of Bursa, so he entrusted his son Orhan to complete this major task, while he retired in his capital.

[121][122] Osman is considered the founder of the Ottoman dynasty who started an imperial line that would expand to include 35 sultans – rulers of one of the largest and most powerful empires in world history.

[48] Osman's descendants are distributed today in several American, European and Arab countries after the royal Ottoman family was expelled from Turkey in 1924 shortly after the declaration of the Republic, by Mustafa Kemal Atatürk.