As the historical experience tells that "the relationship has never been friendly between neighboring countries," Vietnam-Thailand relationship has not been a cordial one. One of the reasons why Vietnam's relationship with neighboring countries including Thailand has not been friendly was its so-called little Sinocentrism. Fortunately, confrontation between the two could have been regulated because both Champa and Cambodia has played buffer roles. However, with the decline of both Champa and Cambodia the relationship between Vietnam and Thailand has become more confrontational and fallen into the courses of collision. Since the early days southward advance of China which had political as well as economic objectives and the northward advance of Champa has made the Vietnamese history as the one which is full of struggles. Under the circumstances of continuing conflict and collision with Myanmar and Cambodia which was aimed at regional hegemony, Thai history has also been studded with various struggles. In order to overcome these problems the two countries has respectively pursued Southward and Eastward advance policy. As such, the bilateral ties between Vietnam and Thailand has been affected by Champa and Cambodia on the one hand and expansionist policy on the other. Both the Southward and Eastward advance of Vietnam and Cambodia has affected on the two countries' relationship, too. Nonetheless, it has not been so bad as the ones between Vietnam and Cambodia, or Thailand and Cambodia. It was because there were Champa and Cambodia as buffer zones. But then, of course it was not a friendly one because the two were both expansionist countries.