"Because of their identification in Muslim societies as kafirs, "non-believers", Hindus were especially in demand in the early modern Central Asian slave markets.... Probably the greatest factors contributing to the increased supply of Indian slaves for export to markets in Central Asia in this period were the military conquests and tax revenue policies of the Muslim rulers in the subcontinent.... The revenue system of the Delhi Sultanate produced a considerable proportion of the Indian slave population as these rulers, and their subordinate iqta'dars, ordered their armies to abduct large numbers of Hindus as a means of extracting revenue... K. S. Lal's assertion that the forcible enslavement of Indians due to military expansion "gained momentum" under the Khalji and Tughluq dynasties is supported by available figures. ...Unfortunately, there is no means by which to determine precisely how abundant Indian slaves were in early modern Central Asia. It is, however, possible to establish a rough estimate of the proportion of slaves of Indian origin in relation to those of other regions, at least in terms of the slave population of late sixteenth-century Samarqand. A survey of seventy-seven letters regarding the manumission or sale of slaves in the Majmu'a-i-wathcPiq reveals that slaves of Indian origin (hindi al-asl) accounted for over 58 per cent of those whose region of origin is mentioned...."