There is still no universally agreed definition on autism spectrum disorder (henceforth, autism) within the context of increasing prevalence of the condition worldwide. Perhaps the best way to define autism is to trace its developmental history in order to provide us a better insight of its genesis. In the beginning, nobody knew about autism. The biblical records of characters, such as Yusof of Jacob and Rachel in the Old Testament and a sick boy whose father brought him to Jesus to be healed in the New Testament, have provided us with telltale signs of the yet unknown condition. In the East, in the records of the Traditional Chinese Medicine (TCM) during the times from Song dynasty to Qing dynasty, prodromal symptoms of the yet unnamed condition of autism were noted. However, it was the West, in the early 19th century with the great European nosological tradition coming into existence, that the term of autism was eventually coined. Through tracing the developmental history of autism, the authors hope to gain a better understanding of the enigmatic syndromic disorder for the purpose of preparing appropriate inclusive treatment plans for individuals with autism throughout the world.