Iron Peak County is not directly connected to the Red River Tribe's grazing grounds. Transporting goods from other places to Wolf Town and then to Revodan, before transferring them to the Red River Tribe, is like making a big detour.
Transporting goods from Vineta and The Federated Provinces to Paratu usually takes the water route. It's challenging enough to sail upstream, let alone overland, which makes the cost of goods surge significantly. Moreover, the road conditions in Iron Peak County are poor, which also increases costs.
For goods like fabric that have a low unit price, transportation costs are normally one to two times higher than the value of the goods themselves. If there's a detour, transportation costs could rise to three to four times the value of the goods."