Los Zetas, which appeared on the scene in the late-1990s, have raised the bar for cruelty among Mexican Mafiosi. Traditionally, the country's narcotics cartels maximized earnings by working hand-in-glove with police, military officers, intelligence agencies, union leaders, and office holders affiliated with the Institutional Revolutionary Party (PRI), which dominated the political landscape from 1929 to 2000. An informal set of rules benefited both the drug capos and their allies in government posts. On the one hand, officials raked in generous payments from the malefactors for turning a blind eye to-or employing the Federal Judicial Police and other agencies to facilitate-the growing, storage, processing, and export of marijuana, cocaine, heroin, and methamphetamines. In return for this treatment, the kingpins were expected to keep their substances away from children, leave civilians (and especially Americans) alone, and limit their arsenals to weapons less powerful than those possessed by the armed forces.