Despite its role as the premier slaving power in the Northern Black Sea region and the main supplier of East European slaves to the Ottoman Empire in the sixteenth–seventeenth centuries, the Crimean Khanate’s own system of slavery remains understudied. Among the reasons for this are the paucity of extant primary sources of Crimean provenance and the under-utilization of non-Crimean sources. The study proposed will rely on the materials of the Muscovite Ambassadorial Office (Posol’skii prikaz) pertaining to frontier conferences between Crimean and Muscovite diplomats for the purpose of ransom and exchange of slaves, freedmen, and prisoners of war. These materials, held in the Russian State Archives of Early Acts in Moscow, have been used in scholarship only superficially. The paper will focus on the 1649 conference, the only one whose extant records include comprehensive lists of the returning Russian subjects indicating their name, gender, social status, place of origin, and the length of time spent in the Khanate. The paper will demonstrate the value of these materials for an analysis of Crimean attitudes towards captives and of the dynamics of the mass movement of manpower across the East European steppe frontier. The nature of the records of the 1649 conference allows for a quantitative analysis of the repatriated party’s demographic profile. The age and gender distribution of the 878 Russians is skewed towards older people (58%) and women (72%), with 55% of the women reporting having spent upward of twenty years in the Crimea. This data indicates the perceived diminished usefulness of older people, especially women, as slaves or even as manumitted residents in the Khanate. The willingness of their owners and of the Crimean authorities to allow the ransom and exchange of such a comparatively large number of slaves and freedmen on one single occasion suggests that these people were viewed as a disposable means of commercial, political, or personal expediency. This attitude correlates with the steady influx of newly captured East Europeans into the Khanate and with a similarly steady outflow of some of the captives to the Ottoman slave markets. The materials under discussion also help us envisage the movement of enslaved and manumitted manpower across the Crimean-Muscovite section of the East European steppe frontier at the time as two sizable, though uneven, currents going in the opposite directions.