Then you can also argue CHINA has "the hottest startup culture outside the US", based on NASDAQ http://www.nasdaq.com/screening/companies-by-region.aspx?reg...

Also among the top 10 unicorns by valuation (http://fortune.com/unicorns/): 6 from US, 3 from China and 1 from India.

Of course, the answer really depends on what you mean by "startup culture".