Development of the banknote began in the Tang Dynasty during the 7th century, with local issues of paper currency, although true paper money did not appear until the 11th century, during the Song Dynasty.
A contract typically does not have to be notarized. A notary public (or simply notary) provides an acknowledgment that the signature appearing on the document is that of the person whose signature it purports to be. There is a requirement that some documents be notarized, such as a real property deed.
All names on the purchase contract do not need to be on the Deed. I have done loans where there are people on the sales contract and the loan, but not on the Deed. I have also done loans where there are people on the sales contract and Deed, but not on the loan.