> Boys of about 13 would be captured from areas to the north of the Persian empire, and trained to become an elite force for the personal use of the sultan or higher lords. The Arabic word Ghulam (boy) was sometimes employed for the bodyguards they would become. The boys would be sent by the caliph or sultan to enforce his rule as far afield as Spain (Venice and Genoa were major players in their transportation despite Papal interdictions) and sold to the commanders of the Islamic governments of the region. Under their new masters they were manumitted, converted to Islam, and underwent intensive military training.

Think about the mass human history involved in that: each Mamluk was either bought from a desperate family or (more likely) captured in raids in which many of his friends and relatives were no doubt slaughtered; he was carried thousands of miles from anywhere he knew or recognised; then he was 'freed,' with no choice but to fight on behalf of those who'd bought him. No doubt many of them were subject to torture and abuse.

It's very similar to the Janissaries, who were taken from Christian villages in the Balkans and Anatolia (modern-day Turkey), made to convert and then trained to serve as soldiers for the Ottomans.

The mind boggles at the centuries of boys taken from their families at forced to fight on behalf of their kidnappers.