Here's a quick timeline of Hasbro's corporate history, including major acquisitions. We also have a brief history of Hasbro organized by the name of companies acquired.
Hasbro is founded by Henry and Merrill Hassenfeld (it was then known as Hassenfeld Brothers). The company originally sold textile remnants. It soon moved into manufacturing pencils and other school supplies; the first toy manufactured by the company was Mr. Potato Head in the late 1940s.
Hasbro acquires Milton Bradley. In 1968, Milton Bradley had bought Playskool. This acquisition included The Game of Life, Candy Land, Twister, Battleship and Axis and Allies.
Hasbro acquires Tonka. In 1987, Tonka had bought Kenner Parker Toys. In 1968, Parker Brothers was bought by General Mills and in 1985, Parker Brothers had been spun off with Kenner Products which became Kenner Parker Toys. This acquisition included Monopoly, Clue, Risk and Sorry!.
Hasbro acquires Avalon Hill. Avalon Hill had bought 3M Games in 1976. This acquisition included Acquire, Diplomacy and History of the World.
Hasbro acquires Galoob.
Hasbro acquires Tiger Electronics.
Hasbro acquires Wizards of the Coast. In 1997, Wizards had bought TSR. This acquisition included Magic: the Gathering, RoboRally and Dungeons and Dragons.
Avalon Hill becomes a subsidiary of Hasbro's Wizards of the Coast division.
Hasbro acquires Cranium, Inc., publisher of more than four dozen games and a variety of books and toys.