Bithynia in the context of "Paphlagonia"

The rise of the Ottoman Empire is a period of history that started with the emergence of the Ottoman principality (Turkish: Osmanlı Beyliği) in c. 1299, and ended c. 1453. This period witnessed the foundation of a political entity ruled by the Ottoman Dynasty in the northwestern Anatolian region of Bithynia, and its transformation from a small principality on the Byzantine frontier into an empire spanning the Balkans, Caucasus, Anatolia, Middle East and North Africa. For this reason, this period in the empire's history has been described as the "Proto-Imperial Era". Throughout most of this period, the Ottomans were merely one of many competing states in the region, and relied upon the support of local warlords (Ghazis) and vassals (Beys) to maintain control over their realm. By the middle of the fifteenth century the Ottoman sultans were able to accumulate enough personal power and authority to establish a centralized imperial state, a process which was achieved by Sultan Mehmed II (r. 1451–1481– ). The conquest of Constantinople in 1453 is seen as the symbolic moment when the emerging Ottoman state shifted from a mere principality into an empire therefore marking a major turning point in its history.

The causes of Ottoman success cannot be attributed to any single factor, and they varied throughout the period as the Ottomans continually adapted to changing circumstances.

Hipparchus (/hɪˈpɑːrkəs/; Greek: Ἵππαρχος, Hípparkhos; c. 190 – c. 120 BC) was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry, but is most famous for his incidental discovery of the precession of the equinoxes. Hipparchus was born in Nicaea, Bithynia, and probably died on the island of Rhodes, Greece. He is known to have been a working astronomer between 162 and 127 BC.

Hipparchus is considered the greatest ancient astronomical observer and, by some, the greatest overall astronomer of antiquity. He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and by Meton of Athens (fifth century BC), Timocharis, Aristyllus, Aristarchus of Samos, and Eratosthenes, among others.

Constantine I (27 February 272 – 22 May 337), also known as Constantine the Great, or known mononymously as Constantine, was Roman emperor from AD 306 to 337 and the first Roman emperor to convert to Christianity. He played a pivotal role in elevating the status of Christianity in Rome, the Edict of Milan decriminalising Christian practice and ceasing Christian persecution. This was a turning point in the Christianisation of the Roman Empire. He founded the city of Constantinople (now Istanbul) and made it the capital of the Empire, which it remained for over a millennium.

Born in Naissus, a city located in the province of Moesia Superior (now Niš, Serbia), Constantine was the son of Flavius Constantius, a Roman army officer from Moesia Superior, who would become one of the four emperors of the Tetrarchy. His mother, Helena, was a woman of low birth, probably from Bithynia. Later canonised as a saint, she is credited for the conversion of her son in some traditions, though others believe that Constantine converted her. He served with distinction under emperors Diocletian and Galerius. He began his career by campaigning in the eastern provinces against the Persians, before being recalled to the west in AD 305 to fight with his father in the province of Britannia. After his father's death in 306, Constantine was proclaimed as augustus (emperor) by his army at Eboracum (York, England). He eventually emerged victorious in Civil wars of the Tetrarchy against the emperors Maxentius and Licinius to become the sole ruler of the Roman Empire by 324.

Pontus (Ancient Greek: Πόντος Pontos) was a Hellenistic kingdom centered in the historical region of Pontus in modern-day Turkey, and ruled by the Mithridatic dynasty of Persian origin, which may have been directly related to Darius the Great of the Achaemenid dynasty. The kingdom was proclaimed by Mithridates I in 281 BC and lasted until its conquest by the Roman Republic in 63 BC. The Kingdom of Pontus reached its greatest extent under Mithridates VI the Great, who conquered Colchis, Cappadocia, Bithynia, the Greek colonies of the Tauric Chersonesos, and for a brief time the Roman province of Asia. After a long struggle with Rome in the Mithridatic Wars, Pontus was defeated.

The kingdom had three cultural strands, which often fused together: Greek (mostly on the coast), Persian, and Anatolian, with Greek becoming the official language in the 3rd century BC.

Nicaea (also spelled Nicæa or Nicea, /naɪˈsiːə/ ny-SEE-ə; Latin: [niːˈkae̯.a]), also known as Nikaia (Ancient Greek: Νίκαια, Attic: [nǐːkai̯a], Koine: [ˈnikεa]), was an ancient Greek city in the northwestern Anatolian region of Bithynia.

It was the site of the First and Second Councils of Nicaea (the first and seventh Ecumenical councils in the early history of the Christian Church). The Nicene Creed, which was composed at the First Council, takes its name from the city. It was also the capital city of the Empire of Nicaea following the Fourth Crusade in 1204, until the recapture of Constantinople by the Byzantines in 1261. Nicaea was also the capital of the Ottomans from 1331 to 1335.

Flavia Julia Helena (/ˈhɛlənə/; Ancient Greek: Ἑλένη, Helénē; c. AD 246/248 – 330), also known as Helena of Constantinople and in Christianity as Saint Helena, was a Greek Augusta of the Roman Empire and mother of Emperor Constantine the Great. She was born in the lower classes traditionally in the city of Drepanon, Bithynia, in Asia Minor, which was renamed Helenopolis.

Helena ranks as an important figure in the history of Christianity. In her final years, she made a religious tour of Syria Palaestina and Jerusalem, during which ancient tradition claims that she discovered the True Cross. The Eastern Orthodox Church, Catholic Church, Oriental Orthodox Churches, Anglican Communion, and the Lutheran Church revere her as a saint.

The Council of Chalcedon (/kælˈsiːdən, ˈkælsɪdɒn/; Latin: Concilium Chalcedonense) was the fourth ecumenical council of the Christian Church. It was convoked by the Roman emperor Marcian. The council convened in the city of Chalcedon, Bithynia (modern-day Kadıköy, Istanbul, Turkey) from 8 October to 1 November 451. The council was attended by over 520 bishops or their representatives, making it the largest and best-documented of the first seven ecumenical councils. The principal purpose of the council was to re-assert the teachings of the ecumenical Council of Ephesus against the teachings of Eutyches and Nestorius. Such doctrines viewed Christ's divine and human natures as separate and distinct (Nestorianism), or viewed Christ as solely divine (monophysitism). The Council of Chalcedon issued the Chalcedonian Definition, stating that Jesus is "perfect both in deity and in humanness; this selfsame one is also actually God and actually man." The Council's judgments and definitions regarding the divine marked a significant turning point in the Christological debates.