Mark Katz has been focusing on the topic of revolutionary waves for several years.According to him, a wave commences when a major revolution transpires in a particular nation within the international system.Soon after this central revolution takes place, subsequent revolutions can be expected in other countries. At times, these affiliate revolutions only occurin the same region as the central revolution. This can be noticed if the first major revolutionary wave of the twenty-first century is taken into consideration.Towards the beginning of 2011, the authoritarian government in Tunisia was removed from power after a series of demonstrations.Following this central revolution, affiliate revolutions happened in other Arab states like Egypt and Yemen.