Answer:
Iron and Bronze Age.
Step-by-step explanation:
According to the widely accepted Kurgan hypothesis or Steppe theory, the Indo-European language and culture spread in several stages from the Proto-Indo-European Urheimat in the Eurasian Pontic steppes into Western Europe, Central and South Asia, through folk migrations and so-called elite recruitment. The 1st millennium BC was the period of time between from the year 1000 BC to 1 BC.