Derebeys were required to provide military assistance in time of war, but ruled and administered their own territories, in full freedom in practical terms, and often forming local dynasties.
Their emergence was often sparked by the gradual abandonment of the timar system administered by the military fiefdom of sipahis, and the tendency of the central government to sub-contract tax revenues as of the 18th century, receiving a determined sum from the derebey and outsourcing on them the task of collecting from the taxpayers themselves.
Through their collection and control of tax revenues in their region as well as only providing armed men for the sultan's wars when it benefitted their interests, the derebeys demonstrated a lack of centralized authority in the Ottoman state during the 18th and early 19th centuries.
Selim's successor, Mahmud II (who followed the year-long reign of Mustafa IV), oversaw the decline of the derebeys as Ottoman government became increasingly centralised and administration was conducted by appointed governors.
Many members of derebey families left lasting works serving general welfare, while others were also involved in bitter struggles that gave rise to public revolts, such as that of Atçalı Kel Mehmet Efe.