Well, prior to the 1600's, it was the dominant economy on the planet, and then during the mid-later Qing Dynasty, there was the critical leadership error in not sufficiently investing in the military instead of investing everything in economic growth.

As a result, China was invaded over and over again by colonizers who levied punitive fines for losing the war. And then there were a series of revolutions. (I know, I was born in a part of Shanghai that's commonly called "the French Concession.") The Bolsheviks were the first to give a bunch of that money back ... maybe because they wanted an ally or because they had a conscience.

Oh, also the Versailles Treaty, which ended WW I, involved a clause that gave Shandong province to Japan (from German control), which caused students to take to the streets in protest against the KMT who ratified it, the political party that eventually lost popular support and went to Taiwan and prevented the international community from recognizing the CCP's government as official China because the KMT maintained that they're the official China.

Is that what you're referring to?

> China is 3000 years years old and still considered an emerging market.

It depends on how you define "China", "3000 years years[sic] old", "still" and "emerging". China has been a "developed market" a few times throughout its history. The modern China (ROC and PRC) lagging behind the Western world in part is due to industrialization in Europe.