Yap's achievement in the postwar recovery of the mining industry established Kuala Lumpur as the economic centre of the peninsula. As the acknowledged leader of the Chinese community he had been given the powers of a Malay ruling chief by the British except for the right to tax, a restriction he easily evaded. Through his control of the tin market, his ownership of local "farms" (monopolies on the sale of items such as opium and exclusive control of activities such as gambling, prostitution, racketeering and loan sharking), and his diverse business interests, he amassed a considerable personal fortune.