a grammar question

only certain people knew how to write, and for thousands of years, professional people called scribes wrote about daily life and trade.
cuneiform gave countries of the ancient world a way of transcribing (their) history.
my question is the pronoun their which is between brackets refers to what?
in my today's exam my answer was that it refers to "countries"
but my teacher says that it refers to people
please tell me the correct answer