@WunWun
The nation has the largest population in the world. It's got a rapidly expanding middle class. The external markets are equivalent to twice it's own population. The external market will increase to four times its own population in the next 100 years. It produces a range of luxury items which it has a monopoly on such as silk. Might a nation plausibly be able to increase the demands for its goods to a sufficient level based on its own middle class? Is the external market big enough?
These folks are big on global exploration with the world being completely explored in 150 years. The nation had dominated the markets for tea, silk, copper, paper and printed books, porcelain, lacquerware, jewelry, rice and other grains, ginger and spice in Europe, Africa, North America, South America, Central America, Asia, Oceania and the Middle East for a couple of centuries by the 1200s (which is when the 500 year timer to the next industrialized nation begins). the Americas are going to eventually be devastated by disease following contact but will continue trading with their limited population.
Africa will develop a rapidly expanding middle class in about 200 years. This timeline has kingdoms built by the native peoples of Siberia in 300 years. Trade with the outside world is established in 200 years and technology from the outside world enters their society. The introduction of potatoes and other crops from around the world allows their population to triple in the 100 years after first contact (200 to 300 years from the current point in the timeline). This creates a region friendly to the nation we've been talking about with a population of 120 million and a rapidly expanding middle class 100 years after first contact.
I've got the nation making contact with the Aztecs in about 120 years. They've got plenty of gold and buying power but the nation has a population of 100 million, quite a bit larger than the Aztecs. I'd expect their buying power would drop quite significantly once disease starts spreading through the Aztec Empire.