Kung fu panda chinese timeline?

I like the movie. Just wondering about the timeline, pertaining to ancient china. It definitely passes 400 BC, and it must be somewhere during 6th century AD due to fireworks but it might be more over since the bad guy had a navy, and the Imperial navy wasn't formed until like the 12th century AD. I'm just curious.|||I don't think it's meant to be set during any specific time, but rather pulls elements from various points in Chinese history.