Don't let all the swordfights and dragons cloud the discussion. Game of Thrones is a family drama. It's about a handful of bloodlines going to war over land, love, and profit. They constantly intermingle, backstab each other, and succumb to infighting. Everyone knows the Starks, the Lannisters, and the Targaryens, but other noble houses demand attention. Look at House Martell, the mighty family that made the deserts of Dorne worth living in.
A Song of Ice and Fire is a massive, sprawling narrative that covers around seven million miles of land mass and enough critical events to fill several world history textbooks. Following every influential figure in Westeros would take up even more space than the books already do. The show was even more restrained. Both works give fans a taste of lesser-known characters without letting them know them well.
How did House Martell take power?
House Martell is the noble house in charge of Dorne. Dorne is thought to be the first part of Westeros to be inhabited by humans. The First Men crossed a land bridge from the old continent Essos to the shore of what would become Dorne. The bridge was swiftly destroyed, and the First Men spread across Westeros. Dorne is barely capable of supporting life. It's covered primarily by a brutal desert and surrounded by rocky shores. The First Men lived alone in Westeros for thousands of years before the Andals came. The newcomers overran Westeros, destroying or subjugating most of the First Men. War consumed the continent, including the deadly shores of Dorne.
Dorne was divided between countless petty kings who squabbled over territory for centuries. Everything changed when the Rhoynar people arrived on Dorne's shores. The Rhoynar were fleeing conquest by the Valyrians, who had established an all-consuming empire on Essos. Ten thousand ships approached, led by the mighty warrior princess Nymeria. Every petty king turned Nymeria and her armies away, fearfully holding onto the scraps of power they'd fought and died for. Only one leader saw Nymeria for what she was. Mors Martell fell madly in love with Nymeria the moment he saw her. He proposed marriage almost immediately, and she accepted. The newly established House Martell dominated Dorne with the power of Nymeria's Rhoynar army. After Mors' tragic death in battle, Nymeria continued to rule Dorne, establishing a noble line that would shape the continent as it is today.
How did House Martell rule?
Dorne stands out from the rest of the Seven Kingdoms in many large and small ways. The influence of Nymeria's Rhoynar heritage can be felt in almost every aspect of Dornish culture. Rulers of Dorne are called princes and princesses rather than lords or kings. Unlike most kingdoms, Dorne's throne is passed to the eldest son or daughter of the previous ruler. Dorne is generally more socially liberal than the rest of Westeros. There are fewer taboos around sexuality and a much looser understanding of honor. The Martells exemplify the vibe of the Dornish people. They're passionate and clever. The lesson they took from Mors and Nymeria is that some battles can only be won with a silver tongue.
Under House Martell, Dorne was never conquered. Aegon Targaryen unified six of the seven kingdoms in his bloody conquest. He attacked Dorne, but the kingdom's geographical hostility and House Martell's guerrilla tactics forced him to retreat. The Dornish were briefly defeated on the battlefield by King Daeron I Targaryen, but the kingdom was never conquered as the Targaryen menace was repelled by an unstoppable rebellion. From this accomplishment, House Martell took the words "Unbowed, Unbent, Unbroken." Their leadership created a plentiful isolationist nation in an otherwise consistently nightmarish continent.
Did House Martell ever lose power?
There was technically a period during which a Martell did not sit upon the throne of Dorne. It only occurred in the show, it didn't last long, and it still kept the family in charge. Oberyn Martell died at the hands of Gregor Clegane. He died defending Tyrion Lannister in a trial by combat. Oberyn's death enraged his wife, Ellaria Sand. Oberyn was the father to eight bastard daughters, nicknamed the Sand Snakes. Ellaria and the Sand Snakes demanded vengeance against House Lannister, but Oberyn's brother Prince Doran refused. The Sand Snakes assassinated Doran and his heir, took the throne, and pledged allegiance to Daenerys Targaryen to fight the Lannisters. By the end of the series, an unnamed Martell is back on the throne.
Of all the noble families, House Martell is certainly the most fun. No systematic culture of incest, no self-destructive commitment to honor, no tarnished legacy to desperately outrun. It's almost all victory for the Martells. From their rise to power through the simple strength of love at first sight to their rule as unconquered heroes, House Martell earns their excellent tagline. Of course they don't get much of the spotlight. Game of Thrones is about miserable people betraying each other in increasingly disgusting massacres. That's why the one big Martell moment in the show is Oberyn's death. The story of Mors and Nymeria is simply too (morally) good for Game of Thrones.