Use the following databases to find a company's history:
International Directory of Company Histories (Gale Virtual Reference Library)
MarketLine - Enter the Company name in the search box then using the right side pull down, select Companies. Find the company in the list of results, and click on the History link in the Table of Contents on the right side of the page
Mergent Online - Search for the Company, find the company in the list of results, and click on the History tab within Company Details. Note that Mergent only covers public companies.