 From the turn of the 19th century until 1887 city of Rostov-na-Donu and all the Taganrog uyezd were part of the governorate, but before the census of 1897 took place they were transferred to the Don oblast.Note that the biggest city of the guberniya was the city of Rostov-na-Donu while Taganrog was not much smaller and the third in size.Here is the data on them