Not only the Pashas (governors) of Trabzon until the 19th century, but real authority in many of the cazas (districts) of each sanjak by the mid-17th century lay in the hands of relatively independent native Laz derebeys ("valley-lords"), or feudal chiefs who exercised absolute authority in their own districts, carried on petty warfare with each other, did not owe allegiance to a superior and never paid contributions to the sultan. This state of insubordination was not really broken until the assertion of Ottoman authority during the reforms of the Osman Pasha in 1850s.