You’ve no doubt heard that the legendary Muhammad Ali recently passed away at the age of 74. And you probably already know that his real name was Cassius Clay before he joined the Nation of Islam and decided to become Muhammad Ali. Amazingly, Clay was only 12 years old when he made his amateur boxing debut and had already won an Olympic gold medal by the time he turned 18. So here’s some of the earliest existing footage of this iconic figure, as you can see him spend his teen years developing into the most famous boxer of all time. R.I.P.