If you read the first article, you know that the Three Kingdoms in the Three Kingdoms Period were Wei, Shu and Wu. The Kingdom of Shu was led by Liu Bei.
Liu Bei had two brothers. One is a tall, bearded, loud man named Zhang Fei. The other one is Guan Yu. Liu Bei used to be of the Han Family (the royal family of the Han Dynasty). But after the fall of the Han Dynasty, he resorted to selling grass shoes and mats for a living. One time, out of chance, Liu Bei chanced upon Guan Yu and Zhang Fei. They all sat down for a drink, and found that they shared many of the same ideals. So, in the peach garden owned by Zhang Fei, they took an oath of brotherhood. Their oath was : 我们虽然不是同年同月同日生，但愿同年同月同日死。Though the flavor text on Peach Garden Oath says something different, probably due to space constraints, the literal translation is : “Although we were not born in the same year, or the same month, or on the same day, we will die on in the same year, in the same month, and on the same day.”