The first tahrfahnii were rescued by the Pantheon of Light just before thier homeworld was destroyed by a rogue meteor. The world was very mountainous, with temperatures that never rose above 40 degrees. As time went by they made thier homes on Myrinthia. Most are loyal to Arlan but some are loyal to the human noble houses. They do tend to be nomadic, especially in thier young adult years. (about 20 years old). They reach middle age around 70, and most tend to gain weighht about then.
Halflings eat a lot in the spring and summer, but very little in the winter. In temperatures that reach below -40 degrees, they start to go into a hybernative state. Aside from this, they are identical to halflings in the PHB 3.5.