Season 5 of the HBO television series “Game of Thrones” has just ended -- and many fans are still stunned by the shocking events of the season finale. The show is based on the book series “A Song of Ice and Fire” by author George RR Martin, who has acknowledged that many backstories and small details from the books are not addressed in the TV series.

In a recent interview, Martin spoke about the origins of the Targaryens and about the history of Westeros. Business Insider shared a short clip from an event at the 92nd Street Y in New York City, where Martin gives an in-depth look at the Targaryens. In the show, Daenerys Targaryen (played by Emilia Clarke) has become one of the most important characters. However, her deceased relatives -- particularly the Mad King and her brother Rhaegar Targaryen -- are also mentioned quite often.

The Targaryens have been rulers of Westeros for hundreds of years. But Martin explains that they are not actually Westerosi. They came from a place called Valyria, located across the Narrow Sea. The ruins of Valyria were seen in Season 5, when Tyrion (Peter Dinklage) and Jorah (Iain Glen) were attacked by the stone men.

Martin explained that the Valyrians were powerful people who dabbled in dark magic and pyromancy. They bred dragons and rode them into battle against their enemies. Even though other groups may have bigger armies, dragons are formidable weapons and no one could compete with the Valyrians.

They ruled with a structure similar to the Roman Republic, where a select few families held power. Unfortunately, an event that Martin calls “the doom” fell upon Valyria some 400 years ago. Valyria was wiped out overnight and the flames engulfed all of the lords and their dragons. The Targaryen family was saved from the doom because they had some kind of premonition. They left Valyria and settled into Dragonstone Island near Westeros. It is now known as the location of Stannis Baratheon’s keep.

When the doom came to Valyria, the Targaryens were the only Valyrian family left. Aegon Targaryen and his sisters conquered the seven kingdoms of Westeros on the backs of three dragons. Their family ruled for hundreds of years but their dragons eventually died and were believed to be extinct.

The rule of the Targaryens ended when Robert Baratheon launched a rebellion under the premise that the Crown Prince Rhaegar kidnapped his bethrothed, Lyanna Stark. Robert won the rebellion and killed Rhaegar. Meanwhile, Jaime Lannister (Nikolaj Coster-Waldau) killed King Aerys who has lost popularity amonthe people and was referred to as "Mad King."

In the current storyline, Daenerys Targaryen is plotting to return to Westeros to reclaim the throne that her family lost. The sixth book of the series is still being written and the TV show isn’t expected to resume airing until spring 2016. Fans of both the show and the books are now in the dark about Daenerys’ fate and the future of House Targaryen.

Martin has vowed to concentrate on finishing the sixth installment on the book series. Filming for Season 6 is expected to start in July.