Ye runs a $42-billion-a-year oil business in China, (No. 229 on the Fortune Global 500), yet few in China know much about the mysterious tycoon or the firm he created, CEFC. Ye bought a collection of oil ­assets in his twenties and ­secured loans from state-owned banks to expand abroad, a privilege for a private company. CEFC has oil agreements in Kazakhstan, Qatar, Abu Dhabi, and Chad and has gone into ventures with state-owned giants to transport oil to China, making him a rare powerful private player aligned with the Chinese government.