This book about the History of Money was quite a challenge, most of the historical research is done by Level Chinese but we wanted to make sure that we were as accurate as possible in the illustrations so finding reference photos for example is not really possible except for cases where we have found pictures of ancient artifacts- but most or all evidence of any symbols and details are long gone. Due to the complexities of ancient history (ancient civilizations developing at different paces and not keeping accurate records or having their records destroyed), and because the ancient origins of economic systems precede written history, it is impossible to trace the true origin of the invention of money and the transition from "barter systems" to the "monetary systems."