What does this sentence mean? I dnt understand what it is saying

Question

As for the Sasanid rule, a well-engrained class system was in place defining from birth whether one would be a priest, warrior, secretary, or commener.

Answer 1

In that society people had few choices for the life or career. If your parents were farmers, you had to be a farmer. If your father could read, then his sons would learn to read.