Xu Zhi-cai was a renowned physician during the Northern and Southern Dynasties, born into a family of medical practitioners. His ancestor was Xu Xi, a native of Danyang in the Southern Dynasty, known as the "Xu Clan of the East Sea." Xu Xi's son, Xu Qiutian, and Xu Qiutian's sons, Xu Daodu and Xu Shuxiang, were all famous physicians. Xu Daodu's son, Xu Wenbo, and his relative, Xu Jian, were also well-known for their medical expertise. Later, Xu Jian was captured by the Northern Dynasty and eventually served in the Northern court. Xu Zhi-cai was the grandson of Xu Wenbo and the sixth son of Xu Xiong, also known as Xu Liu, who was also captured by the Northern Dynasty. He served in the Northern Wei Dynasty, rising to the rank of Prince of Xiyang, hence he was also known as Prince Xu. Xu Zhi-cai, styled Shimao, could recite the Classic of Filial Piety at the age of five, understood its main ideas by eight, and was summoned to be a student at the Imperial Academy at thirteen. His medical skills were exceptional, and he was highly reputed in the northern regions. He authored Yaodui and Pediatric Prescriptions, with a particular depth in the study of materia medica and formulas, leading some to attribute the later ten kinds of formulas to his creation. Additionally, Xu had insights into gynecology, and his special monthly care during pregnancy was based on the methods of nourishing the fetus from the pre-Qin period Qing Shi Zi, which were significant for maternal hygiene and eugenics. Xu also wrote Prince Xu's Prescriptions, Eight Generations of Prince Xu's Family Proven Prescriptions, Xu Family Secret Prescriptions, and Leigong Yaodui, all of which are unfortunately lost. The Xu family's service from the South to the North played a positive role in the exchange of medical knowledge between the southern and northern regions.