Answer: The collection of tribute.
Step-by-step explanation:
The system of taking boys into the military ranks of the Ottoman Empire is known as Devshirma. These young men were recruited and trained as the most elite Ottoman soldiers known as the Janissaries. This system is similar to taking tribute, and sometimes when the rulers of a particular country were unable to pay tribute, the Ottomans would take boys from them to serve the sultan for the rest of their lives.