Refers to wrestling storylines in which a group of wrestlers, normally wrestlers who had recently appeared in one promotion, then appear in another promotion. In some cases, this happens suddenly without advance warning or notice, and usually involves the invaders attempting to take the promotion over. The concept originated in Japan, following the demise of the IWE in 1981. Due to the lack of competition brought on by the territorial system used in the United States at the time, the idea would remain unknown there through the 1980s. A prototype invasion angle did occur in Memphis in late 1983 involving Randy Savage and Lanny Poffo, late of their father's "outlaw" ICW promotion. The best known examples of invasion storylines are The Outsiders, which evolved into the nWo, during the 1990s, and The Invasion, which occurred in 2001, when WCW and ECW went out of business.