Mahamud Yalavach promoted a system in which the government would delegate tax collection to tax farmers who collect payments in silver. Yelu Chucai encouraged Ögedei to institute a traditional Chinese system of government, with taxation in the hands of government agents and payment in a government issued currency. The Muslim merchants, working with capital supplied by the Mongol aristocrats, loaned at higher interest the silver needed for tax payments. In particular, Ögedei actively invested in these ortoq enterprises. At the same time the Mongols began circulating paper currency backed by silver reserves.