Final answer:
Cyrus the Great was the first leader of the Persian Empire, expanding it across Central Asia and ruling with fairness. Under Darius I, the empire's bureaucracy and satrapies managed vast territories. Direct evidence of Darius I's reign is provided by the Behistun Inscription.
Step-by-step explanation:
The first leader of the Persian Empire was Cyrus the Great. He led his forces against various enemies and expanded the empire throughout Central Asia. Cyrus continued the practice of finding loyal leaders and treating his conquered enemies fairly, which kept uprisings to a minimum. His policies of expansion led to conquests in present-day Afghanistan and beyond, even up to the steppes where he encountered the Scythian nomads.
The Achaemenid Empire, founded by Cyrus the Great, became a grand imperial state that at its peak under Darius I, controlled a vast territory from the Balkans to the Indus River valley. To administer this immense empire, a strong centralized bureaucracy was developed, with satraps governing different regions. Notably, Cyrus's fairness is also attested by the remaining historical records, such as the Behistun Inscription, which serves as direct evidence of the reign of Darius I and gives insight into the latters rise to power and the policies of governance.