The University of Campridge released an interactive Bitcoin mining map and statistics about the networks hashrate.
These are the locations of mining facilities and while in the map it might not be very obvious it is a fact that most of the networks power originates from China.
China is accountable for 65% of Bitcoin's mining hashrate which secures the blockchain network.
Of course this is a danger and can become a problem. Chris Larsen, Ripple's executive and co-founder expressed recently his concerns on this matter, with an article he posted on "The Hill".
https://thehill.com/opinion/technology/513082-the-tech-cold-war-is-here-and-the-us-isnt-winning
Quoting Chris Larsen:
At least 65 percent of cryptocurrency mining is concentrated in China, which means the Chinese government has the majority needed to wield control over those protocols and can effectively block or reverse transactions.
It is a problem for Bitcoin that China is controlling the network. The chinese government can take over mining facilities on their soil and essentially control the network.
The major threat for Bitcoin is the centralization of miners in a country that opposes Bitcoin and effectively banned it in September 2017.
Nice one