If your culture repels immigrants, actively or not, it's probably dying.

Wow ! This pretty much explains how California became a hotbed of innovation and creativity.

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Pretty amazing.
I found this way more interesting than the thumbnail image advertized it as. Completely worth seeing!

Since they mention it's based on a Google DB, I will go out on a limb and say it is probably quite euro-centric. A more fully-featured data set would most likely show much more movements in the Middle-East (Persian empire, Muslim golden age having preceded the Renaissance) and around China (because you don't get to be the largest economy in the world for 18 of the last 20 centuries by standing still and doing nothing).