And we don't know exactly why it declined. Might have been climate change, drying up of a river, might have been a natural disaster, it might have been an influence of other peoples. And what we're gonna talk about in this video is the next significant period in the history of South Asia. And it involves the migration or the introduction of another group of people, we believe another group of people, and that's the Indo-Aryans. Let me write this down. Indo-Aryans, sometimes referred to as just the Aryans, who we believe began to migrate into modern day Pakistan and northwest India at right about the same time that the Indus Valley Civilization was declining. And some historians actually believe, well maybe the Indus Valley Civilization declined because of them.