As a relatively economically and culturally developed dynasty in history, the Song Dynasty has been criticized by posterity in terms of military affairs. However, both the Northern Song Dynasty and the Southern Song Dynasty were important dynasties in the history of the mainland. However, in the history of the Song Dynasty, this dynasty also has many mysteries that future generations still do not understand, such as the sudden violent death of Zhao Kuangyin, the founding emperor of the Northern Song Dynasty, and the imperial throne was inexplicably passed to his brother Zhao Guangyi, a mystery that was called "the axe sound of candle shadows" by posterity. After the fall of the Northern Song Dynasty, Zhao Jian established the Southern Song Dynasty, and from zhao shuo onwards, his fertility was weak, and this was retribution for posterity. Although the emperor later transferred to Zhao Kuangyin's line, he was still not prosperous, and the emperor's fertility was very weak. Nine emperors of the Southern Song Dynasty, which lasted 153 years, and only one princess was married, which is indeed strange.

Scarce princess
The Northern Song emperors before Emperor Huizong of Song had many princesses, but after Zhao Chou gave the Song Dynasty a new life, the situation was different. The four emperors Of Song Gaozong, Song Ningzong, Song Lizong, and Song Duzong had no heirs, and even few princesses.
According to the "Wulin Past Events", "Since the southern crossing, the princess has not been able to marry, and the princess of the Zhou Han kingdom of the Duli Sect has surrendered", it is recorded that only the daughter of Song Lizong, the princess of the Zhou Hanguo, was married. Other emperors also gave birth to 8 princesses, but some of these princesses died shortly after birth, and some died early before their fathers succeeded to the throne as emperors. Therefore, the only one who really married as a princess was the daughter of Song Lizong.
Song Lizong was a long-reigning emperor of the Southern Song Dynasty, he sat on the throne for more than 40 years, but for more than 40 years, there were few children, in 1238, that is, in the second year of Jiaxi, the harem of Song Lizong gave birth to a prince, but this prince died two months after birth. Three years later, Jia Guifei gave birth to a daughter to Song Lizong, who was already 37 years old at this time, and Song Lizong was very excited about the birth of this daughter. The "Biography of the Princess of Song Shi" records: "The emperor has no children, and the princess is born and loved very much." The emperor had no sons, and regarded the only princess as a pearl in his hand, first sealing the princess of Ruiguo and then the princess of Shengguo.
When the princess grew up, Song Lizong wanted to give his daughter a good son-in-law. In 1259, the first place in the imperial examination was Zhou Zhenyan, and Song Lizong wanted to recruit a donkey, but he did not expect that the princess thought that she was old and did not agree. Seeing that the princess was older, Song Lizong was also anxious about the marriage of this precious daughter.
A grand wedding
Emperor Lizong of Song finally chose Empress Yang's nephew Yang Zhen as his son-in-law. Because Song Ningzong had no children, he chose Song Lizong to be the crown prince and thus inherit the throne. In the process of inheriting the throne, Empress Yang played a decisive role in enabling Song Lizong to succeed to the throne smoothly. Therefore, the choice of Empress Yang's nephew was a favor that Emperor Lizong thanked Empress Yang for her help.
In April 1261, Song Lizong decided to hold a grand wedding for his daughter. According to the "Past Events of Wulin", this marriage was unprecedented, the scene was grand, and it was the only time that the emperors of the Southern Song Dynasty solemnly married a princess. On the day of the wedding, Yang Zhen "often wears jade belts, rides horses to Hening Gate, Yi Tiao, to Donghua Gate, and greets them with goose coins and jade horses." The princess carries nine four phoenix crowns, and the sleeves are wrapped around the sleeves, and the front of the princess is raised." Because it was the emperor's daughter who was married, many elderly figures of the Song Dynasty were present, as well as the personnel of the imperial family.
According to the record: "The queen personally sent, riding on the Kowloon Mandarin." The crown prince rides on a horse, and the fence is doubled on the left and right", and such a pomp and circumstance is only a royal wedding. But in this wedding, there was actually no princess relative. As emperor, Emperor Lizong of Song could not have attended the wedding in person. The princess's mother died prematurely, and the queen was not related to the princess by blood. Even the crown prince of Song Lizong was inherited and was not related to the princess by blood. Therefore, from the perspective of relatives, the princess only has one relative left, Song Lizong.
After the princess married Yang Zhen, she was not as loving as people thought, because it was actually a political marriage. Moreover, Song Lizong did not marry his daughter far away, in order to see his daughter, Song Lizong let people build a luxurious villa next to the Jiahui Gate, and the princess and the horse lived in this villa, and Song Lizong could usually see his only flesh and bones. According to the "Biography of the Princess of Song Shi", "FeiLou Pavilion Road, Miyuan Palace Garden, Emperor Chang Yu Xiaoyuan from the palace people through the princess first." It can be seen that this villa is very luxurious, and it also shows that Song Lizong attaches great importance to his daughter.
Emperor Lizong of Song again made his daughter a princess of the Zhou Han Kingdom and Yang Zhen an envoy to the Qingyuan Army. No one expected that in the second year of marriage, the princess would fall ill and die soon after. Due to the short time she married Yang Zhen, she did not leave any children. It is regrettable that Princess Zhou Hanguo, as the only princess of the Southern Song Dynasty, did not expect to die early after marrying more than a year ago.
Reasons for lack of heirs
Regarding the low fertility rate of the emperors of the Southern Song Dynasty, some people say that this is the retribution of Zhao Guangyi's descendants, but this statement is suspected of feudal superstition.
The Emperor of the Southern Song Dynasty was indeed not fertile, in fact, it had nothing to do with "retribution", it was just a natural phenomenon. Some experts say that it is also a coincidence that several infertile emperors of the Southern Song Dynasty rushed together. There is also a belief that the Emperor of the Song Dynasty was poisoned by alchemy, resulting in inability to have children, which is only a legend. History only records the phenomenon of the Southern Song Emperor not having children, and does not study the reasons for the emperor's low fertility.
The Southern Song Dynasty did not live a very comfortable life in the south, as we think, singing and dancing. The Southern Song Dynasty had many internal and external troubles, and any emperor who reigned had to bear the pressure of the nomadic tribes in the north and also face the huge pressure of recovering the lost land of the Northern Song Dynasty. Under various pressures, the emperor's fertility was also affected.
Although the Southern Song Dynasty medical treatment is very developed, but the advanced medical level is lacking, the ancient children died more, mainly the medical level can not be reached, in fact, the Southern Song Emperor did not suffer from "infertility", only because of the birth of children early death, the number of heirs is small.
In addition, there were not many women in the harem of the Southern Song Emperor, unlike other dynasties, the emperor's harem had many concubines. This is also a reason for the emperor's lack of heirs.