Screamo (also referred to as skramz) is an aggressive subgenre of emo that emerged in the early 1990s, emphasizing "willfully experimental dissonance and dynamics". It was pioneered by San Diego bands Heroin and Antioch Arrow and developed in the late 1990s mainly by bands from the East Coast of the United States such as Orchid, Saetia, and Pg. 99. Screamo is strongly influenced by hardcore punk and characterized by the use of screamed vocals. Lyrical themes usually include emotional pain, death, romance, and human rights. The term “screamo” has been frequently mistaken as referring to any music with screaming vocals.