The Annan zhiyuan/An Nam chí nguyên 安南志原 by Gao Xiongzheng 高熊徵 (1636-1706) is an important source for premodern Vietnamese history which very few scholars have made use of, and those who have, have only done so minimally. It was compiled in the seventeenth century by a Chinese scholar who appears to have relied on materials obtained during the Ming occupation of Vietnam (~1407-1427), including local records. Some of the information it contains is unique, and very interesting.
The following passage is a case in point. It is about crocodiles, or what some people in Vietnam used to say about crocodiles. What I find interesting about it is the part at the end where it talks about crocodiles having many eggs, and that after they hatch, some babies descend into the water while others take to the land. That sounds a lot like Âu Cơ and her 100 sons. . .
In the two prefectures of Tân Bình and Thuần Hóa there are crocodiles which look like giao [蛟, a type of dragon], and are over two trượng long. They are very strong. They use their tales to grab people traveling on the water and swallow them.
In the past, people were often taken away by the crocodiles. These people would use their hands to squeeze the [crocodiles’] throats, and the crocodiles would not swallow them. The [crocodiles] then left them alone, and [the people] escaped death.
Whenever there is a storm, the crocodiles float on the surface, and people gather to watch them.
A crocodile can produce some several tens of eggs. When they hatch, those which descend into the water become crocodiles while those which ascend onto the shore become peculiar snakes and worms. Sometimes the mother will eat them to not let them multiply.