In 1841, Britain, France, Russia, Prussia, and Austria signed a treaty agreeing to suppress slave trade. Opposition to slave trade was not always the same thing as abolishing slavery in one's own dominions: Britain, France, Prussia and Austria had already abolished slavery in their home states, although not in all of their colonies, while Russia would not free its serfs until 1861. The Ottoman Empire abolished slave trade from Africa in 1847, although it was not until 1882 that it abolished slavery throughout it territories, it having been already abolished in Egypt in 1877.
In the US South, railroad companies routinely owned slaves. Most of the Southern railways prior to the Civil War were built with slave labor. Much historical research remains to be done concerning the details of the relationship between slavery and railroads in the South.
South Carolina outlawed teaching slaves to read and write in 1740; Virginia did so in 1819. After the Civil War and emancipation, resistance to the education of blacks continued in the US and continues in some circles to this day, although today most no longer dare to express this opposition with complete frankness. If you doubt this, take a good look, in person, please, at a few inner-city public schools and public libraries in the US. While you're there, please take note of how much is being done with such appallingly meagre resources.
The earliest prominent African-American classical scholar of whom I know was William Sanders Scarborough (1852-1926), college president, author of a popular Greek grammar. Gradually, the Classics departments in the US have grown more diverse. Gradually. They cannot be said to have covered themselves with glory in this regard.
Although writing in the Latin language existed as early as the 7th century BC, the earliest writers of Latin to achieve enduring fame were Livius Andronicus (c284-c204 BC), Plautus (c251-c184), Ennius (239-169) and Terence (195-159), and both Livius Andronicus and Terence were born slaves and set free in recognition of their talents. There is some disagreement about who was the very greatest writer of Latin; some say Vergil, some say Cicero, some say Ovid, some say Sallust. Some say Horace, who like the other 4 lived and worked in the 1st century BC. Horace's father was born a slave. In ancient Rome, there most definitely were some major class barriers, and yes indeed, slavery was very widespread; but when it came to literature, the writing of slaves and former slaves and the sons of slaves was mentioned in the same breath as the writing of Emperors and Senators, and, with the exception of some Emperors known to be dangerous because of their vanity and need for flattery, was praised or criticized on its literary merit with no regard to its author's social position.
The Khyber Pass was an important part of the so-called "Silk Road," which was actually several land routes reaching from as far west as Europe to as far east as China, and the major land route between Asia and Europe for thousands of years. Columbus was looking for a passage to India -- and in 1492 until he died in 1506 he thought he had found it -- because in his time and until, well, until the rise of railroads, on long journeys sea travel was generally much quicker than land travel. Besides silk, popular items of trade on the Silk Road included gold, silver, ivory, diamonds, emeralds, rubies, jade, fur, lacquer, pomegranates, carrots, spices, porcelain, weapons, and, of course, human slaves.