Most likely, they came from the Caucasus areas that are north of all of those mountains we talked about. There's evidence as far back as 7000 BCE, which is like the beginning of the Neolithic era, right? That they were extracting their teeth and filling cavities, that they were domesticating animals and growing food. But for whatever reason, these northern people came through the passes that the mountains gave them into this valley, and they figured out quite quickly that this was the place that you want to settle because the land is just so fertile. So we do know around 3500 BCE, as the Egyptians were building their pyramids, these people were setting the first stones for their city walls in these villages that are going to pop up along the Indus River and all of those tributes and into that fertile plain that we talked about. Harappa and Mohenjidaro are the two biggest archaeological dig cities that they have found, and what they have found is pretty incredible. All of the cities were laid out in the same grid structure, unlike the other cities, which were really jumbled and not planned out very well.