This is the 3912th most frequent Russian word.
вьетнам
Vietnam (a country in Southeast Asia).
In this sentence, 'Вьетнама' is in the genitive case, showing possession or association with the noun 'history'.
Я интересуюсь историей Вьетнама.
I am interested in the history of Vietnam.
Here, 'Вьетнаму' is in the dative case, used with the preposition 'по' when indicating movement across a location.
Мы путешествовали по Вьетнаму.
We traveled around Vietnam.
In this example, 'Вьетнама' is in the genitive case again, used with the preposition 'из' to indicate origin or source.