Many have cited the influence of the series of revolutions in Central and Eastern Europe in the late 1980s and early 1990s, particularly the Velvet Revolution in Czechoslovakia in 1989. The police attacked a peaceful demonstration by students (mostly from Charles University) – and, in time, contributed to the collapse of the communist government in Czechoslovakia. However, the roots of the pacifist floral imagery may go even further back to the non-violent Carnation Revolution of Portugal in April 1974, which is associated with the colour carnation because carnations were worn, and the 1986 Yellow Revolution in the Philippines where demonstrators offered peace flowers to military personnel manning armored tanks.