What's interesting is that Vietnamese share some words with those in Chinese which are in the same meaning and shares similar sound. Like Đáp àn means "答案" in Chinese, which is pronounced "Dá'àn." And those I hope are not sheer coincidence..
Like the Japanese, they also borrowed over a large span of time, so even some words that do not resemble Chinese have a distant relationship. It has been suggested that the Vietnamese language is a sort of mix between Chinese and Viet-Muong that developed from migrations and mixing. Thus, the Vietnamese language is vastly different from its more conservative siblings.
Actually a huge part of Vietnamese consists of words borrowed from Chinese.