1 Cash - Nguyên Phong Thông Bảo imitation coinage

The Nguyên Phong Thông Bảo inscription presents an immediate historical puzzle: the Nguyên Phong reign belongs to Trần Thái Tông, dating to 1251–1258, yet these pieces were cast centuries later by southern lords who had no legitimate claim to that era's authority. The Nguyễn lords — and later the Tây Sơn — tolerated or actively produced imitation cash of older reign titles, partly because established inscriptions carried commercial trust that a new name could not instantly command.

Fabric and casting quality vary considerably across this long production window, with the cruder examples likely attributable to provincial or unofficial furnaces rather than any central mint.