Tinker

In Middle-Earth a tinker is a travelling craftsman, especially a copperworker, bartering with tinware such as pots and pans or who repairs cauldrons but may be skilled in many other types of handicraft and small trade.Tinkers are often looked down upon as Rogues.

Tinkers in Eriador
Especially in Eriador there were many wandering tinkers.These Tinkers might have been forced to take on a nomadic or semi-nomadic lifestyle after the wars of Angmar and could be considered a tribe on their own.

speculations
The many tribes of Tomb Robbers, Traders and maybe the Eglain of LOTRO could be seen as eriadorian Tinkers.