I want to know the answer to the following question:
What king ruled Persia in 520 BC?
All the background I'm provided with is that "In 530 BC Cyrus the Great, King of the Persian Achaemenid Empire crossed the Hindu-Kush mountains to seek tribute from the tribes of Kamboja, Gandhara and the trans-India region (modern Afghanistan and Pakistan).". Is that enough to answer the question?