Years before the events of Etrian Odyssey IV, Tharsis was a small town with little to attract tourists beyond the view of the legendary Yggdrasil in the distance. The land around Tharsis was infested with monsters, making exploring or settling the lands any closer to Yggdrasil quite dangerous. It seemed inevitable that the town would collapse.
The invention of the Skyship saved the town from ruin, ushering in an economic and population boom. This new mode of transportation allowed for speedy travel across the land, bypassing the dangerous areas below. It also provided a means to tackle the previously unexplored lands surrounding Tharsis, attracting adventurers from across the world. The count of Tharsis promised those adventurers fame and fortune to anyone who could reach Yggdrasil.