Humans have been around for 200,000 years. The world's first civilisation, Mesopotamia, emerged just around 12,000 years ago. I imagine there is no necessary period of time it takes for a civilisation to emerge from the emergence of humanity. Mesopotamia took around 188,000 years to emerge after humans first appeared, but I imagine that was due to different contingent chance events or circumstances that were specific to it. I imagine if things had been slightly different, it could have taken 250,000 years, or 150,000 etc. On the timeline from humans emerging up until the present day, civilisation has only been around for a small proportion of that time - 12,000/200,000, so you could easily imagine the first civilisation emerging much sooner or much later - maybe in 40,000BC, or maybe later than the present day. Why is it then that almost all world civilisations emerged not long after Mesopotamia emerged (not long relative to the 200,000 years we have been around for). Apart from a small number of small remote tribes, there are civilisations everywhere that have their roots from a long time ago, not that long after Mesopotamia emerged, all with their roots within just some thousand of years after Mesopatamia emerged. Why is this? It might make sense that this is because civilisation spread from region to region, but the only problem with this is that my understanding is that in most instances of different peoples meeting, some sort of civilisation already existed amongst both peoples - the native Americans had civilisations, as did the Africans and south Americans when europeans arrived. Wouldn't this all also explain why some civilisations are more advanced than others. If one emerged after 188,000 years and one after 190,000 years, that 2000 years can have a big effect on advancement due to the exponential nature of advancement, but the 2000 year gap can just be explained by minor contingent chance events or circumstances rather than broad general fundamental differences since it's only a small fraction of the total time since humans first emerged.