It seems like the OP is a troll of some sort but I will still weigh in on this issue. The richest country during the Middle Ages was the Song Dynasty.
The Song economy was characterized by privatization and joint stock ventures. Its irrigation was good and domestic demand served as a catalyst for wider spread deforestation to support a fuel-hungry industry. The Song eventually picked up burning coal and hydraulic pumps to fuel industry, which was unmatched at the time. In 1796 the British produced 125,079 tons of iron. This figure was matched 718 years earlier in 1078, when the Song Dynasty produced 125,000 tons of iron.
1280 is a year after the Song's fall but serves as a great indicator of what the Song were capable. At the time in a district in Yangzhou, workers accidentally lit a fuse in an arsenal. The fuse combusted the gunpowder storage, mines, bombs, and rockets, causing perhaps the largest man-made explosion for centuries to come. The blast killed a hundred men instantly and hundreds more, hurled the arsenal's debris, beams, and surrounding trees 5 km away, shook roof tiles 48 km away, and left a crater 10 ft deep. Whether the distance is an exaggeration or not, it showed that the Song had the economic and military-industrial capacity to mass-produce gunpowder, bombs, and rocket weapons in such numbers that could cause a massive shock wave.
To address responses to TDM's use of GDP per capita. Yes, the numbers are closer to guesstimations. However, there are good reasons to assume that per capita GDP of a Song commoner is quite high and that their living standards was reasonably good for their times.