Star Trek: 10 Crazy Facts About Klingons
The legendary warriors are not as straight forward as they seem.

The relationship between the Federation and the Klingon Empire is complicated at best, in any Star Trek continuity. First contact didn't go well, leading the two galactic powers to fight for many years. Even when peace was finally achieved, it was tenuous at best. Even as allies, the Klingons are difficult neighbors to have. There's a good reason for that.
Most people who know the Klingons understand that they are a warrior race who operate on a strict code of honor. Those are the basics, the common facts that everyone in the Alpha Quadrant knows about them. But what they don't all know is what a bunch of screwballs they are. Klingons live life out loud, rarely hiding their true feelings.
You can almost always be guaranteed that they're going to take the direct approach in virtually any situation, no matter how much diplomacy should have been used. From drinking until they can't stand up right before a fight to unexplained biological metamorphosis, Klingons are nothing if not interesting. That's why Star Trek fans have been fascinated with Klingons since the first time Kirk ran afoul of them.
10. They're Basically Space Vikings

The warrior aspect of Klingon culture has always been there but it wasn't always a defining trait of their species. As time went on, honor and combat became increasingly important, eventually becoming the qualities they were best known for. Even new enemies from the other side of the galaxy like the Jem'Hadar were aware of their reputation and sought to fight them.
Klingons are driven by that sense of honor, a rigid caste system and a lust for combat. They fight for territory, and while they don't value wealth the way a Ferengi does, Klingons are more than happy to loot while they kill. Does all of this remind you of anyone?
For all intents and purposes, Klingons are space Vikings, roaming the galaxy in search of combat and plunder. It's almost like the people who created and refined this fictional species took inspiration directly from Earth's history.