It’s a World History Listicle you didn’t know you wanted or needed. I get that. But who wants to be blindsided when Aunt Linda suddenly brings up the unification of China under Khubilai Khan? How will you respond to Uncle Joe’s claims that the Mongols were wanton murderers without some prior research? Well, fear not, fellow turkey warrior. I have compiled your battle plan for you, so you can defeat your familial enemies and assume your rightful place as Great Khan of the Dinner Table, long may you reign.
If you’re not a Mongol nerd like me - and I’m guessing, just statistically, that you aren’t - you might only know about the founder of the Mongol Empire and haver-of-many-children, Chinggis Khan. (That’s Genghis Khan, for all you incorrect Westerners.) But did you know the Mongol Empire was the second largest empire in world history? That they were the largest contiguous empire in world history? How about their policies of religious toleration? Their two attempts to conquer Japan, both of which failed largely due to inclement weather? What about their policy of meritocratic bureaucracy, or their very, very strict stance on the killing of envoys?
Fantastic! Let’s get started!
(I realize I have telegraphed many of my fun facts. But how will you know for sure unless you read on?)
1. Huge Tracts of Land...
At its height in the late 1200s and early 1300s, the Mongol Empire stretched from China in the east to Hungary and the Caucuses in the west. As I said before, these borders land the Mongols a second-place trophy in the competition for largest empire ever - surpassed only by the British Empire during the 20th century, over which the sun really didn’t set. (Thanks, Australia.) If we’re only counting contiguous empires, however, the Mongols take the proverbial territorial cake.
2. ...With Some Exceptions
You may have noticed from that map that a couple major Asian territories were left unconquered: India and Japan. While there are a number of reasons for these territorial exclusions, the Mongols didn’t conquer India largely because of the transit difficulties posed by the Himalayas, the weather (stocky Mongolian horses, bred for stamina, are not large fans of the humid and swampy terrain), and the growing strength of the Delhi Sultanate in the 1290s. 
As for Japan, not one but two campaigns were launched, one in 1274 and one in 1281, to conquer the island state. However, Khubilai Khan’s fleets were annihilated on both occasions because of typhoons, also called kamikaze winds.  Don’t you just hate it when you conscript your Korean shipwrights to build you a navy, and a storm ruins your plans? I know I do. The Mongols would also be stymied by tropical climates and disease in their attempts to invade Southeast Asia, because as great as they were on the steppe, they could never conquer their one weakness: humidity.
3. Khan-liness is Next to Godliness
My personal favorite tidbit of Mongolian knowledge is their policy of religious toleration - and what’s more, the fact that the Great Khan often considered himself among the faithful of most major religions. During a meeting with Franciscan missionary and explorer William of Rubruck, the Great Khan Mongke (r. 1251-1259) declared, “Just as God gave different fingers to the hand so has He given different ways to men.”  (William of Rubruck’s travel account also happens to be one of the most important texts in Mongol scholarship, largely because the Mongolian language does not naturally have a written script. You get that fact for free.) While this spiritual stance is far more complicated - one might, for example, write a paper on it if one were so inclined - a quick summary could include the fact that khans often patronized different religious groups, took on religious leaders as advisors, and practiced various religious rites themselves. In addition to their native ethos of shamanism, the diverse Mongolian Empire was heavily influenced by Buddhism, Islam, Christianity, Confucianism, and Daoism, to name a few.
4. For the Horde!
The Mongol army was one of the most successful of its time, largely due to the steppe lifestyle (Mongolian kiddos start riding horses very early, and physical skills necessary to steppe survival translate pretty well to combat) and a few specific military tactics and technologies. For one thing, the Mongolian compound bow was superior in range to the European longbow, 350 yards compared to the Western 250 yards. Combined with the supremacy of Mongolian archers, and the caracole strategy in which columns of archers would charge, fire, turn around, and fire backwards while retreating in a brilliant spiral of equine death-dealing, it turns out it was difficult for foreign archers to keep up. Another steppe tactic adapted for international conflict was the nerge. This maneuver was often executed during hunting parties, as huge groups of riders would create a circle around a certain area, the interior of which contained the game being hunted. Over a period of time, this circle would constrict and tighten, eventually trapping the hunted inside while the khan and his commanders could ride through and clean shop. Turning this strategy against other humans, it turned out, could be equally successful. 
5. A People, an Empire, a Horrible John Wayne Film
While I could go on about my favorite historical civilization all day, I will leave with this final fact: the term “Mongol” technically refers to the nomadic steppe tribe native to northern and Central Asia. The Mongol Empire at its height, however, spanned an incredible number of tribes, states, religions, cultures, and ethnic groups: from other steppe tribes like the Tangut, Naiman, and Kereyit, to the Chinese Song Dynasty, to the regional principalities of the Kievan Rus’, to the holdings of the Abbasid Caliphate, to the feudal lands of Hungary. It may be easy to generalize about the Mongols, and assume they were all horseback-riding archers with great mustaches and fluffy hats.
(And this is sometimes true.) But, it would be more accurate to consider them as a historian might: a confluence of diverse peoples from all over the known world, ruled over by an exceptional premodern state.
But basically, as long as you don’t think exclusively of this atrocity:
...we can call it square.
 Pradeep P. Barua, The State at War in South Asia, Lincoln: University of Nebraska Press, 2005.
 Timothy May, The Mongol Conquests in World History, London: Reaktion Books Ltd, 2012.