Throughout history, nations have enthroned monarchs before they’ve reached age 20. Though that may seem shocking to us in the 21st century, it’s understandable when we remember that life expectancies were much shorter in earlier times, and pragmatic decisions were often made by courts and royal families to extend dynasties. 

To find the youngest rulers in history, 24/7 Tempo gathered information from a variety of sources such as Britannica, History, The European Middle Ages, and About History. Only rulers who started their reign before the age of 20 were considered. (In contrast, these are the countries with the oldest rulers.)

Given the youth of these monarchs, many were mostly symbolic leaders at the start of their reign. Important decisions were made through regents and courts until they were mature enough to rule. These situations could be exploited by ambitious advisors to direct the fate of their nations. Such was the case during the reigns of King Charles II of Spain and England’s Henry VI.

Most of the tenures of these young monarchs were not very long – few lasted more than 10 years – as they were felled by disease or died in battle. For royals whose reigns extended more than two decades, such as those of Spanish monarchs Alfonso XIII and Isabella II, their time was filled with internal strife.

Some of the young monarchs on this list died in battle, such as King Wladyslaw III of Poland and Hungary, or eventually succumbed to lifelong ailments, such as King Baldwin IV, felled by leprosy. Assassination was more than just a threat for youthful Roman emperors Elagabalus and Gordian III, who were killed by their own guards or troops. 

Click here to see famous rulers who started their reign before 20

The fate of some of these monarchs had consequences for their nations. The death of Pharaoh Ptolemy XIII while fighting Julius Caesar’s legions led to the end of the Ptolemaic dynasty in Egypt. King Charles II of Spain died without an heir, which led to the War of Spanish Succession and the beginning of the end of Spain’s empire. Pu Yi’s four-year reign ended in 1912, the final chapter of more than 2,000 years of Chinese imperial rule. (These were the last rulers of long gone empires.)