Huaxia Life Insurance logo Three and a half years ago, in the wee hours of the night, the billionaire financier Xiao Jianhua was led out of the Four Seasons Hotel in Hong Kong in a wheelchair, with a sheet draped over his head, and whisked across the border into China. He has not been heard from since, and is believed to be detained by the Chinese government under a form of house arrest in Shanghai. But in a dramatic move Friday, China seized control of his business empire, assets held by his flagship Tomorrow Group, a sprawling and secretive financial conglomerate that consists of banks, brokerages, insurance and trust companies, publicly traded firms and investment vehicles that together were once worth more than $100 billion, according to his former aides. Xiao was one of the world’s richest men — and one of the few businessmen to command a full suite of licenses to do business in China’s highly regulated market for financial services. How that financial emp