When-I-go-to-Vietnam-I-try-to-buy-coin-hoards-and-coins-that-have-been-unearthed-by-the-kilo.-Many-times-these-coin-hoards-contain-many-more-Chinese-coins-than-Vietnamese-coins.-Most-of-the-Chinese-coins-are-from-the-Northern-Song-period.-It-seems-that-the-Vietnamese-suffered-from-coin-shortages-of-their-native-currency-and-must-have-used-these-Northern-Song-coins-over-a-very-long-period.-It-does-seem-that-the-use-of-these-Norhtern-Song-coins-tapered-off-by-the-end-of-the-1600's.-My-theory-is-that-Chinese-traders-used-old-Northern-Song-dynasty-coins-to-trade-with-the-Vietnamese.-These-coins-were-plentiful-and-widely-available-in-China.-The-Chinese-probably-bought-coin-hoards-of-these-Northern-Song-coins-(at-a-discount)-and-then-used-them-to-buy-things-from-Vietnam.-Recently-I-bought-a-coin-hoard-of-mostly-French-Indochina-coins.-They-were-mostly-1-cent-bronze