The Western Lands
They were demoted in power as the wars in the East slowed down, and as the Navigators Guild developed their techniques of sea travel. The Merchants are unable to command the same taxes on sea goods because few traders or travelers are willing to travel with them instead of the Navigators Guild. They saw further upsets to their economic strength when the Machinists Union devised the war machines, a unique and extremely profitable invention which upended the traditional trade agreements.
With the border partially closed, and sea travel being conducted by the Navigators, the Merchants are starting to break apart. They argue internally about tariffs and ways to stay relevant, and are trying to exert considerable pressure on Freeport to take on actively legislating commerce and trade.
As private groups gain more autonomy, the Merchants fight for more legislation and government control over trade, to ensure that they receive part of the pie.