<unk> <unk> <unk> <unk> <unk>  1946, the Viet Minh government (later to become the government of North Vietnam) introduced its own currency, the đồng, to replace the French Indochinese piastre at par. ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️  Question: What years did the revaluations come about?
1951 and 1959<unk>