McDonald's introduced the McDonaldland advertising world featuring Ronald McDonald and other characters in 1971.
McDonaldland was a fictional setting created for McDonald's marketing, presenting the restaurant's mascots as residents of a colorful fantasy world. Its cast included Ronald McDonald, Grimace, Mayor McCheese, the Hamburglar, and several other characters associated with the brand.
The setting helped McDonald's build a connected advertising universe rather than relying only on product-focused commercials. Characters could appear together in television spots, restaurant promotions, toys, and other marketing aimed at children and families.
The year 1971 can be confused with the introduction dates of individual characters. Grimace, for example, also appeared during this early McDonaldland period, while Ronald McDonald had been introduced earlier, in 1963. McDonaldland therefore refers to the broader branded world, not simply to the debut of one mascot.