Answer by taking a quote from the following article:

Zorro (Spanish for "fox") is a fictional character created in 1919 by American pulp writer Johnston McCulley, and appearing in works set in the Pueblo of Los Angeles during the era of Spanish California (1769-1821). He is typically portrayed as a dashing masked vigilante who defends the commoners and indigenous peoples of California against corrupt and tyrannical officials and other villains. His signature all-black costume includes a cape, a hat known as sombrero cordobes, and a domino mask that covers the upper part of his face. In the stories, Zorro has a high bounty on his head, but is too skilled and cunning for the bumbling authorities to catch, and he also delights in publicly humiliating them.

In The Curse of Capistrano, Senor Zorro became an outlaw in the pueblo of Los Angeles in California "to avenge the helpless, to punish cruel politicians, to aid the oppressed." He is the title character, as he is dubbed the "Curse of Capistrano". The novel features extensively both Don Diego Vega and Zorro, but the fact that they are the same person is not revealed to the reader until the end of the book. In the story, both Diego and Zorro romance Lolita Pulido, an impoverished noblewoman. While Lolita is unimpressed with Diego, who pretends to be a passionless fop, she is attracted to the dashing Zorro. The main villain is Captain Ramon, who also has his eyes on Lolita. Other characters include Sgt. Pedro Gonzales, Zorro's enemy but Diego's friend; Diego's deaf and mute servant Bernardo; his ally, Fray (Friar) Felipe; his father Don Alejandro Vega, the richest landowner in California and a widower; Don Carlos Pulido and his wife, Dona Catalina, Lolita's parents; and a group of noblemen (caballeros) who, at first, hunt Zorro but are then won over to his cause.  In later stories, McCulley introduces characters such as pirates and Native Americans, some of whom know Zorro's identity.  In McCulley's later stories, Diego's surname became de la Vega. In fact, the writer was wildly inconsistent. The first magazine serial ended with the villain dead and Diego publicly exposed as Zorro. But in the sequel, the villain was alive and the next entry had the double identity still secret.  Several Zorro productions have expanded on the character's exploits. Many of the continuations feature a younger character taking up the mantle of Zorro.  McCulley's stories are set during the during the era of Spanish California (1769-1821) and, although exact years are often vague, the presence of the Pueblo of Los Angeles means the stories cannot happen before 1781, the year it was founded. Some media adaptations of Zorro's story have placed him during the later era of Mexican California (1821-1846).

How long has Zorro been around?
Some media adaptations of Zorro's story have placed him during the later era of Mexican California (1821-1846).