Well it is speculated that Satoshi had posted on an internet forum about the concept of bitcoin in the early 2000's, around the time that paypal first came out.

FYI to the OP - satoshi did not actually "make" the blockchain, the blockchain is the data of the various blocks and is growing roughly once every 10 minutes, by a maximum of 1MB each time it grows. It seems that most people have answered on here as if you were referring to the Bitcoin protocol