Sublime Porte in the context of "Vassal and tributary states of the Ottoman Empire"

The recorded history of the Crimean Peninsula, historically known as Tauris, Taurica (Greek: Ταυρική or Ταυρικά), and the Tauric Chersonese (Greek: Χερσόνησος Ταυρική, "Tauric Peninsula"), begins around the 5th century BCE when several Greek colonies were established along its coast, the most important of which was Chersonesos near modern-day Sevastopol, with Scythians and Tauri in the hinterland to the north. The southern coast gradually consolidated into the Bosporan Kingdom which was annexed by Pontus and then became a client kingdom of Rome (63 BC – 341 AD). The south coast remained Greek in culture for almost two thousand years including under Roman successor states, the Byzantine Empire (341–1204), the Empire of Trebizond (1204–1461), and the independent Principality of Theodoro (ended 1475). In the 13th century, some Crimean port cities were controlled by the Venetians and by the Genovese, but the interior was much less stable, enduring a long series of conquests and invasions. In the medieval period, it was partially conquered by Kievan Rus' whose prince Vladimir the Great was baptised at Chersonesus Cathedral, which marked the beginning of the Christianization of Kievan Rus'. During the Mongol invasion of Europe, the north and centre of Crimea fell to the Mongol Golden Horde, and in the 1440s the Crimean Khanate formed out of the collapse of the horde but quite rapidly itself became subject to the Ottoman Empire, which also conquered the coastal areas which had kept independent of the Khanate. A major source of prosperity in these times was frequent raids into Russia for slaves for the Crimean slave trade.

In 1774, the Ottoman Empire was defeated by Catherine the Great. After two centuries of conflict, the Russian fleet had destroyed the Ottoman navy and the Russian army had inflicted heavy defeats on the Ottoman land forces. The ensuing Treaty of Küçük Kaynarca forced the Sublime Porte to recognize the Tatars of the Crimea as politically independent. Catherine the Great's incorporation of the Crimea in 1783 from the defeated Ottoman Empire into the Russian Empire increased Russia's power in the Black Sea area. The Crimea was the first Muslim territory to slip from the sultan's suzerainty. The Ottoman Empire's frontiers would gradually shrink, and Russia would proceed to push her frontier westwards to the Dniester. From 1853 to 1856, the strategic position of the peninsula in controlling the Black Sea meant that it was the site of the principal engagements of the Crimean War, where Russia lost to a French-led alliance.

The Crimean War was fought between the Russian Empire and an alliance of the Ottoman Empire, the Second French Empire, the United Kingdom of Great Britain and Ireland, and the Kingdom of Sardinia-Piedmont from October 1853 to February 1856. Geopolitical causes of the war included the "Eastern question" (the decline of the Ottoman Empire), expansion of Imperial Russia in the preceding Russo-Turkish wars, and the British and French preference to preserve the Ottoman Empire to maintain the balance of power in the Concert of Europe.

The war's proximate cause was a dispute between France and Russia over the rights of Catholic and Orthodox minorities in Palestine. After the Sublime Porte refused Tsar Nicholas I's demand that the Empire's Orthodox subjects be placed under his protection, Russian troops occupied the Danubian Principalities in July 1853. The Ottomans declared war on Russia in October. Fearing the growth of Russian influence and compelled by public outrage over the annihilation of the Ottoman squadron at Sinop, Britain and France joined the war on the Ottoman side in March 1854. The Russian advance was halted at Silistria in June.

The League of Prizren (Albanian: Besëlidhja e Prizrenit), officially the League for the Defense of the Rights of the Albanian Nation (Albanian: Lidhja për mbrojtjen e të drejtave të kombit Shqiptar), was an Albanian political organization that was officially founded on June 10, 1878 in the old town of Prizren in the Kosovo Vilayet of the Ottoman Empire. It was suppressed in April 1881.

The Treaties of San Stefano and Berlin assigned areas inhabited by Albanians to other states. The inability of the Porte to protect the interests of a region that was 70 percent Muslim and largely loyal forced Albanian leaders to organize their own defence and to consider the creation of an autonomous administration, as Serbia and the other Danubian Principalities had enjoyed before their independence.

The Principality of Serbia (Serbian: Књажество Србија, romanized: Knjažestvo Srbija) was an autonomous, later sovereign state in the Balkans that came into existence as a result of the Serbian Revolution, which lasted between 1804 and 1817. Its creation was negotiated first through an unwritten agreement between Miloš Obrenović, leader of the Second Serbian Uprising, and Ottoman official Marashli Pasha. It was followed by the series of legal documents published by the Sublime Porte in 1828, 1829 and finally, 1830—the Hatt-i Sharif. Its de facto independence ensued in 1867, following the evacuation of the remaining Ottoman troops from the Belgrade Fortress and the country; its independence was recognized internationally in 1878 by the Treaty of Berlin. In 1882 the country was elevated to the status of kingdom.

Abdul Mejid I (Ottoman Turkish: عبد المجید اول, romanized: ʿAbdü'l-Mecîd, Turkish: I. Abdülmecid; 25 April 1823 – 25 June 1861) was the 31st sultan of the Ottoman Empire. He succeeded his father Mahmud II on 2 July 1839.

Abdulmejid's greatest achievement was the announcement of the Tanzimat Edict upon his accession, prepared by his then Foreign Minister Mustafa Reshid Pasha, which effectively began the Tanzimat era, or era of reorganization, in the Ottoman Empire. He was a mild-mannered monarch, giving the Sublime Porte the autonomy needed for its reform projects. One of the main goals of the Tanzimat was to encourage Ottomanism among the millets to stop rising nationalist movements within the empire, but despite new laws and reforms to integrate non-Muslims and non-Turks more thoroughly into Ottoman society, in the long term, the movement failed.

The Treaty of Bucharest between the Ottoman Empire and the Russian Empire, was signed on 28 May 1812, in Manuc's Inn in Bucharest, and ratified on 5 July 1812, at the end of the Russo-Turkish War of 1806–1812. The Ottomans had done poorly in the war. The Sublime Porte above all wanted to stay out of the impending conflict between Napoleon's France and Russia. The Russians did not want a war on two fronts, thus they made peace in order to be free for the upcoming war with France. The Ottomans had extricated themselves from a potentially disastrous war with a slight loss of territory. This treaty became the basis for future Russo-Ottoman relations.

The United Principalities of Moldavia and Wallachia (Romanian: Principatele Unite ale Moldovei și Țării Românești), commonly called United Principalities or Wallachia and Moldavia, was the personal union of the Principality of Moldavia and the Principality of Wallachia. The union was formed on 5 February [O.S. 24 January] 1859 when Alexandru Ioan Cuza was elected as the Domnitor (Ruling Prince) of both principalities. Their separate autonomous vassalage in the Ottoman Empire continued with the unification of both principalities. On 3 February [O.S. 22 January] 1862, Moldavia and Wallachia formally united to create the Romanian United Principalities, the core of the Romanian nation state.

In February 1866, Prince Cuza was forced to abdicate and go into exile by a political coalition led by the Liberals; the German prince Karl of Hohenzollern-Sigmaringen was offered the throne and, on 22 May [O.S. 10 May] 1866 he entered Bucharest for the first time. In July the same year, a new constitution came into effect, giving the country the name of Romania; internationally, this name was used only after 1877, since at the time it shared a common foreign policy with the Ottoman Empire. Nominally, the new state remained a vassal of the Ottoman Empire. However, by this time the suzerainty of the Sublime Porte had become a legal fiction. Romania had its own flag and anthem; after 1867, it had its own currency as well.

The Treaty of Küçük Kaynarca (Turkish: Küçük Kaynarca Antlaşması; Russian: Кючук-Кайнарджийский мир), formerly often written Kuchuk-Kainarji, was a peace treaty signed on 21 July [O.S. 10 July] 1774, in Küçük Kaynarca (today Kaynardzha, Bulgaria) between the Russian Empire and the Ottoman Empire, ending the Russo-Turkish War of 1768–1774 with major concessions to Russia. The concessions to Russia were not merely territorial; not only was the Crimea Khanate (not Crimea proper) ceded, but Russia also gained the right to construct a Russian Orthodox church in Constantinople, claiming to be the protector of the Orthodox Christians in the Ottoman Empire. This was a pretext for frequent and numerous interventions in the decades to follow. Ottoman Christians started to feel more empowered as European and Christian powers demonstrated their rising influence and political power. Access to Europe's political networks, markets and educational institutions created a class privilege for Ottoman Christians, and scholars often regard the treaty as turning point for relations between Ottoman Christians and the European nations.

The treaty was a milestone in the history of the decline of the Ottoman Empire, as for the first time a foreign power had a say in the governance of the Porte in assuming direct responsibility for the fate of the Empire's Orthodox Christian subjects.