Ancient times are different from ours. Rich people appeared in their generation, and when they made money or developed, they would build ancestral temples. After the ancestral temple was built, he began to write genealogy, but because he didn't know it before, he might write a few that he knew.
From this rich man, their family has developed, and they will keep their genealogy in the future, and the developed rich people will always make friends with many rich people, thus becoming a big family, a big family. They open ancestral temples to worship their ancestors every year, and when they have children and grandchildren at home, they will also open ancestral temples to write them down when they need to write them down.
The development of aristocratic families is sometimes longer than that of some dynasties. They are all people who are not short of money or positions.
These people have a long genealogy, and future generations will know who their ancestors are.
The poor have basically no genealogy. At most, a big ancestral hall with the same surname will be built in a village, and everyone in the family will be placed in the ancestral hall when they die.