Recorded human history spans thousands of years. In that period, entities of all types have gone through name changes. In some cases, those changes were down to a turnover in ownership (Byzantium becomes Constantinople becomes Istanbul) or circumstance (St. Petersburg becomes Leningrad becomes St. Petersburg again). In others, it's a made of prudence. Kentucky Fried Chicken officially calling themselves KFC, for example. That word "fried" is harder to sell in a modern world.