Quote Originally Posted by Renmiri View Post
Around 3000 years ago
- Vast improvements were made in the magic civilization.
- Machina was invented.
- The use of machina became common through the whole of Spira.
- Machina technology reached its peak.

Sorry for not linking to the source but the Cid's knights here might object to links to other forums. Google for it and you will see that it is on at least 3 other forums.
CKs don't care, when it's used as evidence.

This shows that they still required magic to progress in their lives. If you still have magic, there's no point to have machine power to be as high as ours is. The description also says that it reaches its peak, which leads me to believe that machine power must have stagnated, or that the people did not want it to progress further (which would be a very good reason for the Machina War). If something reaches its peak, then it can not progress further.

Don't worry, I can draw loose interpretations from Japanese.