Bitcoin operates on a peer-to-peer network over the Internet, on which several messages are propagating about every created transactions. By carefully analyzing the timestamps of the reception of these messages, we developed a probabilistic mathematical model that assigns Bitcoin identifiers to IP addresses, thus revealing the identity of Bitcoin users. Through the IP addresses, many Bitcoins could be geographically located, which revealed several interesting Bitcoin-related links between countries. To the best of our knowledge, this is the first research that quantitatively analyzes the spatial distribution and flow of Bitcoin.