The first Thain of the Shire was Bucca of the Marish, who founded the Oldbuck family. However, the Oldbuck family later crossed the Brandywine River to create the separate land of Buckland and the family name changed to the familiar "Brandybuck". Their patriarch then became Master of Buckland. With the departure of the Oldbucks/Brandybucks, a new family was selected to have its chieftains be Thain: the Took family (Indeed, Pippin Took was son of the Thain and would later become Thain himself). The Thain was in charge of Shire Moot and Muster and the Hobbitry-in-arms, but as the Hobbits of the Shire led entirely peaceful, uneventful lives, the office of Thain was seen as something more of a formality. The major political power in the Shire was actually held by the Mayor of Michel Delving (the Shire's chief township). His duties included overseeing the post and the "police" force (Shirriffs); he was also obliged to preside at banquets. The Hobbits' numbers dwindled, and their stature became progressively smaller after the Fourth Age. However, they are sometimes spoken of in the present tense, and the prologue "Concerning Hobbits" in The Lord of the Rings states that they have survived into Tolkien's day.
