Original: Examples of Old Persian have been found in present-day Iran, Iraq, Turkey and EgyptRoland G. Kent, Old Persian, 1953 the most important attestation by far being the contents of the Behistun inscription (dated to 525 BCE).
Simplified: Examples of Old Persian have been found in present-day Iran, Iraq, Turkey and EgyptRoland G. Kent, Old Persian, 1953 [ ].