For nearly four hundred years after its foundation, the the Shire had been part of the lands of Arthedain, and under the rule of that land's King. Ultimately, Arthedain fell to the forces of Angmar, and its last King, Arvedui, was lost, leaving the Shire-hobbits without a ruler. They remedied this by choosing a new leader from among themselves, Bucca of the Marish, who was given the title thain, a word simply meaning 'chief'.
Bucca and his descendants, a family known as the Oldbucks, served as Shire-thain for twelve generations. The twelfth Thain, one Gorhendad Oldbuck, left the Shire and crossed the River Brandywine to found Buckland. With his departure, the Thainship passed to a new line, the Tooks, and specifically to Isumbras Took I.
From Isumbras I, the line of the Took Shire-thains continued unbroken to the time of the War of the Ring and beyond. The last recorded Thain was Faramir Took I, the thirty-fourth to hold the title of Shire-thain. The fact that both he and his father Peregrin Took are recorded as the first of that name shows that there must have been more Thains after this time, and the office clearly lasted well into the Fourth Age.
Line of Thains
It is known that there were at least thirty-three Shire-thains, from Bucca, who became Thain in III 1979, to Faramir I, who took on the title in IV 63, more than a thousand years later.
- I Bucca of the Marish (Thain from III 1979) - The first Thain was given the title in III 1979 (379 by the Shire-reckoning) in a time when the northern lands were recovering from a devastating war in which the old kingdom of Arthedain had come to an end. He was succeeded by Thains of the Oldbuck line.
- II-XI Ten Thains of the Oldbuck line (Thains for about 300 years to III 2340) - Bucca was followed by Thains whose names are not recorded, but who took the surname 'Oldbuck' in honour of their ancestor.
- XII Gorhendad Oldbuck (Thain to III 2340) - The line of the Oldbucks came to an end with Gorhendad, who crossed the River Brandywine and founded Buckland, changing his name to Brandybuck. The Thainship passed from him to the Took family, and Gorhendad was succeeded by the first Thain of the Took line.
- XIII Isumbras I (Thain from III 2340) - The thirteenth Thain in line from Bucca, and the first of the Took line. Isumbras' descendants would hold the Thainship for the rest of the recorded history of the Shire.
- XIV-XXI Eight Thains of the Took line (Thains for about two hundred years to III 2683) - The eight Tooks to hold the Thainship after Isumbras I are nowhere named, but we can infer some of their identities from the names of later holders of the office. Among these eight must have been Isengrim I, Ferumbras I, Paladin I and Isumbras II, but no records of their Thainships are known.
- XXII Isengrim II (Thain for 39 years to III 2722) - The twenty-second Thain, and tenth of the Took line. He began the excavation of Great Smials, which would become the seat of the Thains in the Tookland. He became Thain soon after the first pipe-weed was introduced into the Shire by Tobold Hornblower. He was succeeded by his son.
- XXIII Isumbras III (Thain for 32 years to III 2759) - His younger son was Bandobras Took1, the famous 'Bullroarer'. In Isumbras' time the Shire was greatly troubled by Orcs, and Bandobras defeated a band of them at the Battle of Greenfields during his Thainship. Bandobras, though, was Isumbras' younger son - the Thainship passed instead to his older brother.
- XXIV Ferumbras II (Thain for 42 years to III 2801) - He was succeeded by his son.
- XXV Fortinbras I (Thain for 47 years to III 2848) - At the beginning of his Thainship, the Shire would have seen much activity as Dwarves of Durin's Folk travelled westward to settle in the Blue Mountains. He was succeeded by his son.
- XXVI Gerontius (Thain for 72 years to III 2920) - The famous Old Took, who held the office of Thain for a total of seventy-two of his one hundred and thirty years, and had a total of twelve children. During his Thainship, the Shire suffered the dreadful privations of the Fell Winter, and invasions of White Wolves. He was succeeded by the eldest of his many sons.
- XXVII Isengrim III (Thain for 10 years to III 2930) - Due to the Old Took's many years in office, his eldest son Isengrim was no less than eighty-eight years old when he inherited the Thainship. He held it for just ten years and died without leaving an heir. He was succeeded by his younger brother.
- XXVIII Isumbras IV (Thain for 9 years to III 2939) - Like his brother Isengrim, Isumbras came old to the Thainship, being ninety-two when he took office. After his short time as the Shire-thain, he was succeeded by his son.
- XXIX Fortinbras II (Thain for 41 years to III 2980) - Early in his time as Thain there was a sensation in Hobbiton, due to the mysterious disappearance into the Wild - and later reappearance - of one Bilbo Baggins of Bag End. Fortinbras was succeeded by his son.
- XXX Ferumbras III (Thain for 35 years to III 3015) - He was Thain at the time of Bilbo Baggins' famous farewell feast and Birthday Party, which indeed he attended. He never married, and so left no heir. The descent of the Thainship passed to the line of Gerontius' fourth son Hildigrim, and specifically to Hildigrim's grandson.
- XXXI Paladin II (Thain for 19 years to IV 13) - Born in the time that his great uncle Isumbras IV was Thain, Paladin took up a farming life at Whitwell in the Tookland. He was Thain during the War of the Ring, and held the Tookland against the ruffians who invaded the Shire at that time. He was succeeded by his fourth child, but eldest son.
- XXXII Peregrin I (Thain for 50 years to IV 63) - Peregrin Took of the Fellowship of the Ring inherited the Thainship some thirteen years after his return from adventuring in the south, and held the title into his old age. At the age of ninety-four, he gave up the office and rode away once again into the countries of the south with his friend Meriadoc Brandybuck; they were never seen in the Shire again. He was succeeded by his son.
- XXXIII Faramir I (Thain from IV 63) - Named for Faramir the Prince of Ithilien, little is known of Thain Faramir, except that he married Sam Gamgee's daughter Goldilocks. Doubtless he was succeeded by further generations of Shire-thains, but of them we have no record.