When was maori invented?

The Māori language is not "invented". It is a living language with a long history, spoken by the Māori people of New Zealand. It is descended from Proto-Polynesian, a language spoken in the Pacific thousands of years ago.

It's important to understand that languages are not invented, they evolve over time.

Therefore, it's impossible to pinpoint an exact date for the "invention" of the Māori language. It's been spoken and passed down through generations for centuries, and continues to evolve even today.