Simplify the following text for a Grade 11 native English-speaking person.
Original: Their arrival to the region is associated with the first wave of Iranian tribes in the late second millennium BCE ( the Bronze Age collapse ) through the beginning of first millennium BCE .
Simplified: This area was known in Greek as Media or Medea They entered this region with the first wave of Iranian tribes , in the late second millennium BC ( at the end of the Bronze Age ) .