“Dynasty” is one of those sports words, like “choke” or “momentum,” that is functionally useless because no one can agree on an exact definition. For some, a dynasty must include, as a bare minimum, three championships over a condensed time frame. That’s an incredibly—almost unreasonably—hard feat to accomplish.
The Green Bay Packers inaugurated the modern era of the NFL by winning five titles in seven years, from 1961 to 1967—but only two Super Bowls, because the Super Bowl didn’t exist (and therefore the Packers never had to play the AFL champion) for their first three.