For us to attach the label “ancient” something has to have hung around a long time. A millennium is the minimal time: eons and ages are even more deserving of the term ancient. Except for the occasional tree, all things ancient are stone, metal, petrified wood, or papyrus stored in hot sand.
Funny thing about age designation and status. Mayflies live hours and receive no consideration from anyone. Humans gain status through four decades, and lose status after forty decades. Furniture gains status after a hundred years.
Ancient is venerated when applied to the dead; ancient is not venerated when applied to the quick.