This study aims to reveal the conceptual origins of the notion of hassa soldiery and the idea of kul system in the early Ottoman state on the example of janissary corps by using the early Ottoman chronics, fourteenth and fifteenth century vakf registers, foreign memories and a later source of Kavanin-i Yeniçeriyan. A comparative approach referring to the pre-Ottoman and contemporary Turkic-Islamic near eastern states, Turco-Mongol states, as well as the Roman and the Byzantine states, reveals that the terms ghulam, kul or kapıkulu had a different meaning and function in the near eastern tradition and in the Ottoman context which cannot be found in western terminology, even though similar formations can be found in the Medieval states which are similar to the ghulam-kul system of the near east in terms of structure, as a result of the longue duree of acculturation between east and the west.The Ottomans seemed to establish a special form of hassa soldiery in the kul identity of the janissary corps peculiar to themselves.