In pre-imperial Mongolia, slavery had not played any big part, but the Mongol invasions and conquests of the 13th century created a great influx of war captives, which were by custom considered legitimate to enslave, and caused a significant expansion of slavery and slave trade.
The Mongol slave trade was based on war captives and human tributes, and the constant warfare and conquests of the Mongol Empire and their vassal khanates supplied a constant influx of enslaved people to the slave trade network of the Empire.
When the Mongols captured a city, the routine were to enslave people deemed to be suitable for the slave market, such as craftsmen and other skilled artisans.
[2] Another method to acquire slaves were taxation in the form of human tributes from conquered states.
Ethnic or racial preferences: Different ethnicities were preferred for various roles across different regions; for instance, Turkish men were often utilized as slave soldiers in the Middle East, Tartars as household slaves in Italy, and Korean girls as concubines in China.
[5] The slave market was traditionally limited in China, were slavery did not play a big role.
[9] There were no social or religious taboo in China for selling, buying and owning people of the same ethnicity and religion.
[10] There was an established custom in China to enslave criminals and rebels, [11] as well as impoverished or indebted people selling themselwes or their children in to slavery.
[18] One of the most important markets for the Mongol Empire were the Muslim Delhi Sultanate in northern India.
[20] Male slaves for military slavery (Ghilman) were trafficked from China to the Middle East via Central Asia and Iran.
[20] Turkish slave soldiers were transported from the Golden Horde in Central Asia to the Mamluk Sultanate in Egypt via the Black Sea.
After the Siege of Acre, the inhabitants of the city, being Frankish Christians, were deported to the slave market of Baghdad.
[19] In the Ilkhanate in Iran, Mongol soldiers reportedly often owned slaves used to cultivate the land allotted to them.
An example is the Siege of Baghdad of 1258, after which thousands of Arab people of the conquered city were taken as slaves to Azerbaijan or Mongolia.
[20] Genghis Khan was among many recorded warlords who would often employ the mass, indiscriminate murder of men and boys regardless if they were soldiers, civilians, or simply in the way.