“Too much of a good thing can end up being a bad thing.” Between 500 and 1500 AD, many civilizations advanced. Unfortunately, many empires have grown too far, making them unsustainable and failing. However, if they fall, it's usually for a larger reason. Whether it was religious disagreement, weak leadership, or uninhabitable geography, when civilizations like the Mongol Empire, Roman Empire, or Islamic Empire grew too big or too large, they collapsed. For a civilization to be sustainable, it must have a great leader and great means of communication. Without these qualities, running an empire is almost impossible. The Mongol Empire was ruled by Genghis Khan, which meant universal ruler. Although the Mongols were "successful in raids and clan warfare", they failed to govern the people, because they did not enforce enough rules. In fact, Khan didn't know any of the people he managed. He employed foreigners rather than Chinese in high government positions because he believed they were trustworthy since they had no local loyalties. This angered many people, so when Khan died, the Yuan dynasty began to fade and rebellions broke out, leading to the fall of his empire. With so many people in the Mongol Empire, they didn't all speak the same language. The Roman Empire also struggled with these concepts. Diocletian believed that the empire had become too large and too complex for a single ruler. The empire was divided into two parts: the Greek-speaking East and the Latin-speaking West. This made communication between empires extremely difficult. The Islamic Empire faced the death of about a quarter to half of the population due to the Black Death, also... middle of article......Scientific Studies, “The Mongols in the history of the world. Accessed March 25, 2017. 2014 http://afe.easia.columbia.edu/mongols/conquests/conquests_4.htm Diamant, . “Ted” Last edited February 2003. Accessed March 25, 2014. http://www.ted.com/talks/jared_diamond_on_why_societies_collapse University of Wisconsin, last edited September 25, 1998. Accessed March 25, 2014. http://www .uwgb.edu/dutchs/westtech/xmongol.htm.National Geographic, “Steppe”. Accessed March 25, 2014. http://education.nationalgeographic.com/education/encyclopedia/steppe/?ar_a=1. National Geographic, “National Geographic Atlas of the World.” Accessed March 25, 2014. http://travel.nationalgeographic.com/travel/countries/mongolia-facts/ .Beck, Roger B. Interaction Patterns of World History. Evanston, IL: McDougal Littell, 2007. http://www.bellbookandcandlepublications.com/greenwoodsvillage/gor/islam.php