It seems appropriate to believe that Satoshi Nakamoto was simply a single person who created Bitcoin, an individual genius in terms of the media but such innovations usually do not happen in a vacuum environment. No matter how original it may seem, all great scientific discoveries are built on pre-existing researches. One of Bitcoin's pioneers, Adam Back's Hashcash was invented in 1997, followed by Wei Dai's b-money , Szabo's bit gold and Hal Finney's Reusable Proof of Work. The Bitcoin whitepaper refers to Hashcash and b-money as well as other studies covering a variety of research areas. Therefore, many of the people behind the other projects mentioned above are thought to be in the team that created Bitcoin.