Slavery in the Crimean Khanate

According to Muslim law, only prisoners of war captured in war or on a campaign could become slaves in the Crimean Khanate. After several years of service, they were guaranteed freedom. That is why the system of slavery in Crimea was called “open”. What categories of slaves existed under the Crimean khans? Under what conditions could a slave become free? Based on research materials by O. Stepanchenko and O. Rustemov.