The Reach is one of the nine major regions of Westeros, but was formerly a soveign nation known as Kingdom of the Reach, before Aegon’s Conquest. House Tyrell maintains dominion over the Reach from their seat of Highgarden. The Reach is not only one the largest regions of Westeros, but their land is also the most fertile. They yield bountiful crops, exporting to the rest of the continent fruits, vegetables, grains and wines. The fertility of their land makes the Reach the second most wealthy region, only behind Casterly Rock of the Westernlands.
The Reach, originally Kingdom of the Reach, was originally settled by House Gardener, an ancient and now extinct house of Westeros. Many of today’s houses of the Reach, including House Tyrell, trace their lineage back to the ancient House Gardener. For many generations, House Tyrell were stewards to House Gardener. During Aegon’s Conquest, Mern Gardener and the entire Gardener bloodline was wiped out after the Field of Fire. With the depletion of House Gardener, House Tyrell stepped up and surrendered the Reach to Aegon. As result, House Tyrell were made overlords of the Reach and wardens of the south.
Highgarden is the capital of the Reach, ancient castle and seat of House Tyrell. More so than a fortress built for defense during battle, such as Winterfell or Storm’s End, the castle of Highgarden is more of a fairy tale castle – majestic and beautiful. The castle is lined with fountains, courtyards and beautiful flowers. Though the castle was seat to House Gardener for thousands of years, after Harlen Tyrell surrendered Highgarden to Aegon, it was awarded to House Tyrell as their new seat.
More recently, during Robert’s Rebellion, the majority of Highgarden supported the Mad King, rather than join the rebel cause. During the War of the Five Kings, Renly Baratheon returned to Highgarden with Ser Loras Tyrell, and acquired the strength of Highgarden under his banners as he attemped to sieze the Iron Throne. After his death, the majority of Highgarden switched their allegiance to support Stannis Baratheon, until finally forging an allegiance with House Lannister through an arranged marriage between Margaery and King Joffrey.