A brief about social structure, moral values, and common information about ancient chinese culture

Read with CAUTION. Contains SPOILER!

Let me briefly explain the social structure and basic moral values of ancient Chinese dynasties. This will help provide context for the events happening in this drama.

Social Structure / Caste System:
The hierarchy generally looked like this:

Royal Family/Imperial Family > Aristocratic/Noble Families (Duke, Marquess, Earl, etc.) > Scholars and Officials (Zhuang Yuan, Jinshi, Juren, etc.) > Commoners/Working Class (farmers, artisans/tradesmen, merchants) > Slaves > Marginalized/Outcasts (entertainers, courtesans, pariahs).

Note: Sometimes, entertainers and courtesans could be considered above slaves. But generally, they're pretty much in the lowest class of the social structure.
I have no deep knowledge about this, so feel free to correct me.
Children rank in the family.
There are Firstborn, Secondborn, Thirdborn, etc. Also, Legitimate born and Concubine born.
1. Legitimate Firstborn Son (Di Zhangzi): Let's rank it 1 for easier understanding.
  This son held the most prestigious position in the family. He was expected to carry on the family name (including title) and inherit the family property.
  
  If the father loves him so much or if the mother comes from a prestigious family, the firstborn usually will be named heir not long after he is born. This status is typically confirmed unless the child dies, is incompetent, or is ill.
  
  And when his father dies, he automatically becomes the patriarch of the family (which means that all family members need to listen to him).
2. Legitimate Secondborn, we rank it 2
  He has no privileges the same as the firstborn. He can only inherit the title of heir if his brother is incompetent, convicted of a crime, or ill (like the case of Gu Ting Ye in The Story of Minglan, he inherits the Marquis title because of his brother's condition).
  
  However, he also can achieve the title of Duke or Marquess or other title on his own merits and with the support of his brother.
3. Legitimate Thirdborn, etc
  Basically, they have a lower status compared to first and second-borns.
4. Concubine's born son (Shu zi)
  A son born by a concubine only has a chance to inherit the title if no legitimate sons are capable of inheriting it.
5. Bastard son (Shishengzi)
  A child born out of wedlock has very low status and is usually excluded from the family tree, inheritance, and rights.
6. Firstborn daughter (Di zhang nu)
  - If she is biologically born by the legitimate wife and if the family/clan is powerful enough, she usually will be selected as empress (huanghou) or crown princess (taizhi fei).
  - If not, then she could be the princess consort (Wangfei) of some prince.
  - Other than that, she normally married into a noble family as a primary wife (Zhengqi) unless she's from a lower-ranking family (sometimes, in order to climb the ladder, the family will marry her into some noble family as a concubine (Qie).
    
    However, if the mother is dead or the parents hate her, this is a different thing.
7. Legitimate second, third, fourth, etc born daughter
  They practically have the same rights or are slightly lower than firstborns in terms of authority and status. But normally there won't be much difference.
8. Concubine born daughter (Shu nu)
  Like the son, her status is much lower compared to the legitimate daughter. And usually have no chance to marry into a royal or powerful/noble family as primary wife (Zhengqi). At most, she can be the concubine (Qie) of the emperor or some prince.
  
  However, if her family is reputable and she has a good attitude, virtuous, etc, she might be able to marry as primary wife (Zhengqi) to some noble family too (like Ming Lan in The Story of Ming Lan) or if specifically requested by the previous wife (like Luo Shi Yi Niang in The Sword and Brocade).
  Again, it all depends on the circumstances.
  
  But typically, they would become the wife of a lower-ranking official or scholar or a concubine in a noble family.
9. So, after learning about the structures, let's now compare Song Mo and Song Han.
  
  Song Mo -> Firstborn of Duke Ying and Jiang family legitimate daughter. His rank is 1.
  Song Han (previously) -> Secondborn of Duke Ying and Jiang family legitimate daughter. His rank is 2
  
  If something happened to Song Mo, he would be second in line for the succession unless Song Mo had a son.
  
  After the birth secret was revealed:
  Song Han -> A bastard child of Duke Ying and Li Yao Niang, a former courtesan/entertainer and the daughter of a criminal. His rank -999
  
  His biological mother holds a very low status in the social hierarchy, and being born out of wedlock even lowers his status. To learn more about pariah, courtesan, entertainer you can also check A Dream of Splendor (The hierarchy and social stigma might not be entirely the same, given that the drama is set during a different dynasty)
  
  As a result, he has no chance of inheriting the title or family property. He is also very unlikely to marry a daughter from a noble family. Even a concubine's daughter would refuse to be his wife.
  His existence is basically just a laughing stock.
  Even if he one day accumulated merits on his own, his "lowly" background would always hinder him.
  
  But was his situation always this doom? Not entirely. If his father had been powerful enough, had merits, or was an upright person, he could have redeemed his mother and married her as a concubine (though he would still face criticism from all sides). But at least it's pretty doable. In that case, Song Han could be registered in the family tree as a concubine's son.
  As far as he could go, Song Han might also be recognized as a legitimate son under Mrs. Jiang (if he is able to negotiate with Mrs. Jiang).
  
  So, if you think his hostility toward Song Mo or how he eventually became evil doesn’t make sense, just consider his status and what he has experienced so far.
Why do people fight so hard over a mere title?
Take another look at the social structure. The more noble you are, the more respect you receive and the easier your life becomes. Basically, status and title are very important. The same goes for officials - the higher your rank, the more power you hold and the more respect you earn from others.
Royal family
1. The reason Prince Qing is in Liaodong while the Crown Prince is in the capital
  This is because only the Crown Prince has the privilege of staying in the Imperial City, specifically in the Eastern Palace (Dong Gong). Other princes are given their own fiefdoms and are expected to go there once they reach adulthood or after they get married. In Prince Qing's case, he has reached adulthood and was granted Liaodong as his fiefdom.
  
  The same rule applies to princesses, though they are usually given more leniency and can remain in the imperial city until marriage, as they are not seen as posing a threat to the Crown Prince.
  
  Similarly, a Grand Princess (the emperor's sister) must move to her own fiefdom or follow her husband’s family after marriage, and she can only return under special circumstances, such as widowhood, with the emperor's permission.
2. Why do the eunuchs seem to hold so much power?
  Because during the Ming Dynasty, they had a significant influence, although this drama doesn't highlight it much. In that era, the eunuchs ran the Eastern Depot (Dong Chang), and to keep check and balance, there was also the Brocade Uniform Guard (Jinyiwei).
  
  This drama, however, doesn't mention the Eastern Depot and renames the Jinyiwei to Jinwuwei. If you're curious about the power struggles involving these factions, Brotherhood of Blades is a good movie to watch.
3. Power struggle
  Power struggles within royal families have long been notorious. Rebellion, coups, harem conflicts, siblings killing one another, fathers killing sons, sons killing fathers, uncles killing nephews, empresses killing emperors, emperors decreeing concubines to be buried alive, poisoning, etc. - these themes are very common, and we have seen a lot in the drama. It's basically based on historical events.
4. Why can't the emperor simply abdicate and pass the throne to the crown prince to prevent the rebellion?
  First, abdication was very rare in the Ming Dynasty.
  Second, an emperor's abdication could significantly affect political stability, especially since the crown prince lacks a solid foundation to sit on the throne at this point. Given the turmoil and factionalism within the court, it is very unlikely that the emperor could step down.
  
  That’s why, in many cases, the crown prince needs to choose a crown princess from a family with a strong background. This helps him stabilize the court, either by aligning with a powerful general who controls army or with high-ranking officials who have significant influence in the court.
Private army or soldier
Without the lawful approval of the emperor and the acknowledgment of the ministers, no noble family is allowed to raise their own army. If this were to become known to the public, it would be considered a crime of deceiving the emperor (qi zun zi zui) and a crime of plotting rebellion or treason (mou ni zi zui).
It's a Death sentence. Therefore, the existence of the Ding army could never be known by the public.

As for Dou Zhao, she could never have her own soldiers, neither legally nor illegally. Don't confuse this with the people she hired while in the manor. They were simply individuals skilled in martial arts, not actual soldiers. Furthermore, when she married into the Ying family, she couldn't bring them along due to the strict etiquette that needed to be followed.
Marriage
1. Marriage arrangement
  In ancient times, marriages were arranged by the family (typically the father, mother, or family patriarch) unless the individual was granted the privilege to arrange their own marriage by the emperor or empress.
2. A marriage granted by the emperor.
  In this drama, Miao Ansu agrees to the marriage because she has taken a liking to Song Han. However, even if she doesn't want to marry him, she also has no other choice. Rejecting a marriage granted by the emperor is a death sentence and could even lead to the extermination of her clan.
  
  Additionally, a marriage granted by the emperor cannot be easily dissolved unless the husband commits treason or other serious crimes. In such cases, a woman can apply to dissolve the marriage and ask to return to her family home, which needs approval from the emperor or empress.
3. Marrying a wife versus marrying into the bride's family
  - Marrying a wife (Qu Qi)
    refers to when a man takes a woman into his family. In this arrangement, the woman leaves her own family to join the man's. The child born in the family will follow the father's surname.
  - Marrying into the bride's family (Ru Zhui)
    A family, typically a wealthy one or a merchant family with many properties but no male heir, will usually look for a man who is willing to join their family to continue their legacy.
    So, instead of the bride marrying into the groom's family, Ru Zhui is the groom marrying into the bride's family and living in the bride's home.
    In such cases, the children born will take the mother's surname. An example in this drama is Zhao Zhangru. So, Chen Jia most likely married into her family.
4. Marital arrangement
  - Formal marriage with three letters and six rites (Ming Mei Zheng Qu, Shan Shu Liu Li) is the procedure when a man wants to marry a woman as a primary wife (Zhengqi). This process involves several steps, including matchmaking, parents' approval, performing formal rituals (exchanging birth dates, presenting betrothal gifts, setting the wedding date, etc), signing the marriage certificate, and ceremony.
  - Taking concubine (Na qie). This procedure is simpler than a formal marriage, as it does not require the "Three Letters and Six Rites." Typically, the process is hiring a matchmaker, proposing to the parent, giving a simple betrothal gift (or depending on the woman's background), choosing an auspicious date, and ceremony. For women from lower backgrounds, the process is even more straightforward, often with no ceremony, just taking her home.
5. What is a betrothal gift, what is a dowry, and why do people make such a big deal about it?
  - A betrothal gift (pin li) is a symbol of how much the future husband and his family respect and value the bride. If the man truly loves or respects her, he will include as many gifts as he can in the list.
    For example, precious items (jade, treasure), silk, shop, land, money, and everyday necessities (like a set of beds, utensils, etc.).
  - Dowry (jia zhuang) is a symbol of the bride's status within her own family. The more dowry she has means the more her family values her. This also means her husband's family will show more respect towards her.
    The difference between a legitimate daughter and a concubine’s daughter can often be seen through their dowries. A legitimate daughter will have more dowry compared to a concubine's daughter.
    While the betrothal gift typically goes to the bride’s family, some parents might include it in the bride’s dowry as well. The dowry consists of items the bride brings to her husband’s family.
    This is why people make such a fuss about it - it represents a person's status and also the biggest things to rely on other than the husband.
6. Bride's sedan
  When the groom picks up the bride from her family to bring her into his (ying qin), the bride typically sits inside a sedan. There are several types of sedans, from single to twelve. A twelve-sedan procession is usually reserved for royal families, while noble families typically use four to six. High-ranking officials or families of higher nobility, such as dukes, often use eight sedans.
  
  Except for the twelve-sedan procession, any number of sedans can be chosen by the groom and his family. The greater the number of sedans, the more it signifies the groom’s distinguished background and his respect and love for the bride.
7. Types of wifes
  - Primary wife, sometimes referred to main wife or simply wife (Zhengqi), is the woman who marries into the family through the formal process. She is typically the matriarch of the household, responsible for managing the home, and holds the second-highest authority after her husband.
  - Equal wife (Pingqi). A woman who marries into the family as another wife, sharing the same authority as the current wife.
    In certain situations, if a man is already married but wants to marry another woman with a background as strong as his first wife’s, he may choose to make her an equal wife instead of concubine.
  - Stepwife (Jishi). When a primary wife passes away or divorces, another woman can marry into the family as a stepwife or secondary wife. Her status is no different from that of the primary wife. (Luo Shi Yi Niang in The Sword and Brocade is an example of a stepwife).
  - Concubine (Qie). They don't have the authority to manage the household unless there is no primary wife present. They are typically seen as companions to the husband and must follow the arrangements set by the primary wife. Typically, there is no limit to the number of concubines a man can have.
  - Bed servant (Tongfang) is a servant who attends to the master in his bed. If she bears children, her status will usually be elevated to a concubine.
8. The difference between divorce (xiu qi) and separation (he li):
  - Divorce (xiu qi) happens when the wife has committed serious wrongdoing or violated certain rules (Infidelity, infertility, disobedience or misbehaviour, etc). In this case, her dowry is typically not returned unless there is a specific agreement made between the husband and wife.
  - Separation (he li) occurs when the husband and wife mutually decide to dissolve their marriage peacefully. In this case, the wife is entitled to get her dowry back.
    
    In many Chinese dramas, you may see a husband asking for a separation from his wife when something happens to him, such as being convicted of a crime or falling ill.
    
    This is because, in ancient China, if a man committed a crime (unless it was a minor one), his entire family could be implicated, especially his wife and children. This could lead to the wife being labelled as the wife of a criminal and facing a loss of status (from high-ranking lady to commoner). Their children would also suffer, as they would be considered the child of a criminal and would be banned from taking the imperial examination or becoming officials.
    
    For example, in The Story of Minglan, Gu Ting Ye asks for separation from Ming Lan because he doesn't want her to go from being a high-ranking lady to the wife of a criminal, which would severely impact her status and also their children.
    
    In the same case, when a husband is severely ill, he will ask for a separation because he doesn't want her wife to suffer alone in the home.
    When the husband passed away, his wife had to mourn. During the mourning period, which typically lasted three years in the Ming Dynasty (but could be longer depending on the family's status), the wife had to wear plain clothes, not use any accessories, refrain from attending joyful events or banquets, and serve ancestral rites (lots of things). She was also expected to keep a low profile and could not remarry. Most importantly, a widow often bore a social stigma, and people might call her jinx (ke fu), blaming her for her husband's death.
Filial piety is extremely important due to the influence of Confucian teachings, especially to parents.
So why does Dou Zhao have to stop Song Mo from killing his father? Because committing patricide (Shi fu) is a grave sin, an unforgivable sin. There's no way this act could ever be justified, no matter what his father did. If his father committed crimes, the proper course of action would be to expose it and bring it to the emperor, but never to kill him.
This also happens to Ling Bu Yi in Love Like The Galaxy when he is accused of patricide.

Once again, killing a parent violates the rules of filial piety and is basically a death sentence. Even if Song Mo could escape execution, his life would be ruined. The same applies to killing a family member - while not as severe as killing a parent, it would violate the same rules, face a similar punishment, and will be condemned by people.
Why did Son Yi Chun want to kill Song Mo instead of just expelling him from the family tree and removing him as the heir?
Normally, this would be a family matter, but in some cases, depending on the noble family's situation, the removal from the family tree and as an heir requires the emperor's approval, just like the appointment of an heir.
If the emperor found out that Song Mo didn't commit a serious crime, the emperor most likely wouldn't approve the removal draft. Therefore, the easiest solution for Song Yi Chun was to kill him.
Why did Song Mo have to kill the entire household to protect the baby?
Because the baby was the heir to Duke Ding, who was convicted of a criminal that was publicly known at the time. If news of Song Mo keeping the baby were to leak, he would be accused of the same crime as Duke Ding, as well as the crime of deceiving the emperor. This would result in the same death sentence, not only for SM but also for all his followers. The Song family would also likely face exile, if not execution.
So yeah, keeping a little baby could cause a big problem.
Why does the emperor not want to marry the princess to Song Han, and why does the princess reject him in such a manner?
Again, because of his background. By requesting the marriage, Song Han is already slapping the royal family in the face. And the way the princess rejects him isn't just because she doesn't want to marry him but because she wants to humiliate him publicly in the most degrading way possible.

If this were the previous Song Han, the legitimate second son of Duke Ying, the emperor might have agreed to the marriage, or the princess wouldn't have rejected him in the same way.
In ancient times, the etiquette towards noble families, commoners, and those of lower rank were very different.

I hope this information helps you better enjoy the drama.

Note: Of course, this drama doesn't stick strictly to historical accuracy. For more accurate information about the Ming dynasty, it’s recommended to refer to reputable historical sources.