What do you mean by exchanging cattle for horses?

Anyone who has read The Romance of the Three Kingdoms should know.

Legend has it that Sima Yi calculated the word "exchanging cattle for horses" by fortune telling.

Later, when he came to power, he suspected that a minister named Niu in North Korea was trying to seize power, so he killed him.

As a result, there was still a woman in their family who had an affair with a cow surname, gave birth to their descendants and inherited the throne.

I don't know much about that history. But the outline is right.