Short answers, pulled from the story.
The Crimean Khanate was founded by Hacı I Giray in 1441, after he warred for independence against the Golden Horde from 1420. He had been living in exile in Lithuania before separatist Crimean clans invited him to become their khan.
In 1475, Ottoman forces under Gedik Ahmet Pasha conquered the Greek Principality of Theodoro and the Genoese colonies at Cembalo, Soldaia, and Caffa, bringing the khanate under Ottoman suzerainty. From 1524 onward, Crimean khans were appointed directly by the Ottoman Sultan.
Over the period 1500-1700, the Crimean Khanate exported roughly two million slaves from Russia and Poland-Lithuania, mainly into the Ottoman Empire. Researcher Fisher estimates that from 1474 to 1694, as many as a million Polish-Lithuanian Commonwealth citizens were carried off into Crimean slavery.
The decline resulted from the weakening of the Ottoman Empire, the Treaty of Karlowitz in 1699 which outlawed further slave raids, and the growing military power of Russia. Crimean cavalry suffered losses against Russian and European armies equipped with modern weapons, and without slave-raid income, the khan lost support among noble clans.
On the 8th of April 1783, Catherine II intervened in a civil war within the khanate and annexed it as the Taurida Oblast, violating the 1774 Treaty of Kuchuk-Kainarji. Only France openly protested the annexation.
The Bakhchisaray Fountain was commissioned in 1764 by Khan Qırım Giray, who asked fountain master Omer the Persian to build it. It was created to honor his grief after the early death of a Polish woman from his harem whom he loved, so that the stone would weep as he had wept.