Vovinam to demonstrate Vovinam publicly in Hanoi with his disciples in 1940, Nguyễn was invited to teach the art at Hanoi's Ecole Normale, and Vovinam gained in popularity. During the following years, political unrest increased throughout Vietnam; due to the system's nationalist political orientation, the art came under suppression. By 1954, Nguyễn had emigrated to South Vietnam, where he was able to continue to teach and establish Vovinam schools. After his death in 1960, Grandmaster Le Sang continued the development and international promotion of Vovinam until his own death on September 27, 2010. The first Vovinam school outside of Vietnam was
Japanese martial arts rule of thumb, the primary purpose of a "koryū" martial art was for use in war. The most extreme example of a "koryū" school is one that preserves its traditional, and often ancient, martial practices even in the absence of continuing wars in which to test them. Other "koryū" schools may have made modifications to their practices that reflect the passage of time (which may or may not have resulted in the loss of ""koryū"" status in the eyes of its peers). This is as opposed to "modern" martial arts, whose primary focus is generally upon the self-improvement (mental, physical,