Toughskin is a city in Haggar territory.
The city is usually Haggar-controlled, but was taken by Jetstone forces under Prince Ossomer after Haggar took Pantstown.
Real World References
Toughskin is a reference to Toughskins, a clothing line sold by Sears. The first Toughskins products were childrens' jeans made from a blend of polyester, nylon, and cotton.
There is also a line of iPod protective coverings called ToughSkin.