The only mixed-race Dragonmarked House, House Tharashk is populated by both humans and half-orcs, and some orcs who do not actually bear the Mark of Finding which the House is known for. Not quite the youngest House, but definitely the least established of the Thirteen, House Tharashk has neverthelesss found its niche and fast by being able to find rich ore veins and, even more importantly, rich fields of dragonshards. They also have plentiful experience and use in the fields of bounty hunting and being an inquisitive.
House Tharashk has a unique culture within itself that some would say is largely insane. Three major families make up the House, and two of them hold to what many consider to be entirely opposed philosophies. One family is from the tradition of the Gatekeepers, who are charged with keeping the daelkyr imprisoned—and the other family is from a Cult of the Dragon Below, which seeks exactly the opposite. How they manage to live together is unknown, but House Tharashk is deeply prideful of its status. Even its name, Tharashk, is an orcish word meaning Unity.