score:17
Speaking very generally, merchant groups were relatively marginalized in all pre-modern societies. They formed networks across city-states in different regions, but were not allowed to take strong political footholds in more centralized states. Political rulers saw economic power as a threat, a (sometimes necessary) evil and were generally successful in keeping merchants subordinate.
One relative exception that illustrates the rule might be Song China. Merchants were thriving there economically in a way the world had never really seen, but politically they were still pretty subordinate. Most dynasties that followed (most notably the Ming and Qing) frequently cracked down on merchant power and even tried to stop all external trade for long periods of time.
What happened in Europe from the early modern period onward was more or less unprecedented in world history. Merchants started to have formidable political power during the late medieval period in certain parts of coastal Europe, along the Baltic (under the Hanseatic League) and Mediterranean (especially what became Italy). The Republic of Venice was an early and important city-state to be effectively ruled by the merchant class. In time the Medicis managed to take the papacy. I'm not aware of any earlier example of merchants seizing that level of political power. So that might be my direct answer to your headline question.
If you'd like more detail on how merchant classes were constrained in pre-modern societies around the world and how different early modern Europe was from previous patterns, I recommend the book Pre-industrial societies: anatomy of the pre-modern world by Patricia Crone.
Upvote:2
Basically I am trying to paint a vivid mental picture of how the merchant class gained power equal to or above the kings in Europe, China, and India (or anywhere else). Who were the key merchants (what were their names or ethnicities), and what did they do to aid in this transition?
IMHO, you are trying to paint a picture of a world that has never existed! Some merchants or groups of merchants acquired considerable power, but ultimately they all had to bow their heads to their own sovereign or some rival feudal power.
There are some interesting examples, in which merchants could pressure princes into submission, challenge them on the field of battle or gain immense influence as financiers.