Because every day is your birthday. Because right now, on the planet Earth, there are 16 million direct descendants of Genghis Khan, meaning that every day is the birthday of 43,000 of them. So good news, Genghis Khan, your empire might be gone, but your progeny lives on and on and on and on. Happy birthday! Best wishes, John Green. Unfortunately for the Mongols, those guys weren't always working together because Genghis Khan failed to create a single political unit out of his conquests. Instead, after Genghis's death, the Mongols were left with four really important empires called khanates.