maintaining this army involved much higher costs than the taxation of the local economy could sustainably provide, and required subsidies from the central government. such support became unfeasible by the 1850-60s due to the costs of suppressing the taiping and other rebellions in the chinese heartland. the qing authorities in xinjiang responded by raising taxes, introducing new ones, and selling official posts to the highest bidders (e.g. that of governor of yarkand to rustam beg of khotan for 2,000 yambus, and that of kucha to sa'id beg for 1,500 yambus). the new officeholders would then proceed to recoup their investment by fleecing their subject populations.