Margaery Tyrell details House Tyrell's history serving under House Gardener before the War of Conquest and House Targaryen afterwards, before surrendering to Robert Baratheon after he defeated the Targaryen dynasty.
Margaery Tyrell: House Tyrell trace our descent to Garth Greenhand, the legendary first King of the Reach, who made the land bloom. But so too does every noble house around us. It seems dear ancestor Garth "planted" as many flowers as he "plucked". A king should have more consideration for his line, don't you think?
For over a thousand years, the Greenhand's sons and grandsons ruled The Reach as House Gardener. The offshoots of his daughters grew into vast and powerful houses in their own right. Except for House Tyrell. We chose instead to serve our Gardener cousins faithfully as stewards; to manage their stronghold of Highgarden and the daily affairs of the Reach. Our words are "Growing Strong". And under our stewardship the Reach did just that... as did we.
Until a blundering king almost cost us everything. Aegon Targaryen had landed in Westeros. King Mern allied us with the Rock to repel the upstart's army. One can only marvel that King Mern did not reconsider when he saw the living dragons against him. Perhaps he should've sought council from his trusted stewards before he set out... then again, perhaps he did.
At the Field of Fire, Aegon - and let us not forget, his sisters - burned the combined armies of the Reach and Rock. King Mern paid for his misjudgment with his life and that of his ancient family. In a day, the Reach had lost its king, its ruling house, and most of its army.
Thankfully for everyone, my ancestor, Harlen Tyrell, had better sense. Until the maesters sorted out the entail among Mern's cousins, Harlen the steward was acting lord of Highgarden. To ensure peace and life in the Reach he would yield the castle of Aegon. The other castles and families would then follow, as they had since the Dawn Age.
Aegon had a continent to conquer, and the fertile Reach was too valuable to raze. He accepted Harlen's proposal and welcomed our lands into his kingdom. To show his gratitude, Aegon entitled Harlen to Highgarden, the castle his family had served for a thousand years, and made House Tyrell his Wardens of the South; choosing us over older, greater families in the Reach.
Some may question my father for laying siege to the Baratheon's home, instead of marching to aid Prince Rhaegar before Robert could kill him and scatter the royal army. But let us not forget we had already dealt Robert his only defeat of the war at Ashford. If Lord Tywin Lannister had not... "vanquished" the Mad King so suddenly, our siege would've destroyed Robert's home and his brothers and won the war for Aerys.
But when the Targaryens fell, House Tyrell again chose peace and prosperity over war and devastation, and bent the knee to King Robert Baratheon, First of His Name. We returned to Highgarden to manage the affairs of the Reach, as we had for thousands of years - and will for a thousand more. Other Great Houses take lions and wolves for their sigils, and draw their power from the gold in their mountains or the cold of their winters. But mountains run dry, winter yields to spring; and the rose blooms once more.
- King Garth Gardener, "Greenhand"
- King Mern IX Gardener
- King Loren Lannister
- King Aegon I Targaryen, the "Conquerer"
- Queen Visenya Targaryen (not mentioned by name)
- Queen Rhaenys Targaryen (not mentioned by name)
- Balerion, the "Black Dread" (not mentioned by name)
- Vhagar (not mentioned by name)
- Meraxes (not mentioned by name)
- Lord Harlen Tyrell
- King Aerys II Targaryen, the "Mad King"
- King Robert Baratheon (mentioned)
- Lord Mace Tyrell (mentioned)
- Prince Rhaegar Targaryen (mentioned)
- Lord Tywin Lannister (mentioned)
- Stannis Baratheon (indirectly mentioned)
- Renly Baratheon (indirectly mentioned)
- House Tyrell
- House Gardener
- House Targaryen
- House Lannister
- House Baratheon
- House Stark (indirectly mentioned)
- War of Conquest
- Robert's Rebellion