But because of their organization and the consistency, relative consistency amongst these different sites that are so far flung, this is a large distance even on modern terms, but especially if we're talking about four or 5,000 years ago. Because of that, we think that, okay, there must have been at least decent government, administration, or organization at a city-state level, although we're unsure whether there was a connected empire, whether you had an organization beyond that or they all just decided to take each other's standards and symbols and brick sizes and things like that. Now, one of the key mysteries of the Indus Valley civilization is why did it end? It seemed to be this thriving civilization, perhaps the most extensive one. In other videos I talk about right now, the oldest wheel was discovered in Mesopotamia, but some people think that the wheel might have been used even earlier in the Indus Valley civilization. I talk about this period as early as 3300 BCE, but there's evidence that the civilization started much earlier. In the site right over here in Merger, right over here in Pakistan, they think that humans were having simple villages and agriculture as early, there's evidence as early as 7,000 BCE.