SUMMARY

The outbreak of fighting between different drug-trafficking gangs in Mexico can be understood against the background of changes in the Mexican political landscape during the last decades. During the 1980s, there was a loose network of drug smugglers controlling their own "plaza" for drug trafficking. Governmental authority was highly centralized under PRI (Partido Revolucionario Institucional, Institutional Revolutionary Party) rule and by bribing high officials, the drug smugglers could control their businesses without getting interrupted by the authorities. When single-party rule started to give way to local opposition these networks and relationships were transformed, to the advantage of some actors but to the disadvantage of others. The drug cartels started to fight each other for control over territory and previous alliances fell apart.

The Sinaloa Cartel and the Tijuana Cartel have been rivals of the drug trafficking along the Pacific Coast and the smuggling routes into California since the early 1990s. This rivalry led to a turf war in Sinaloa state in early 2004, where lucrative marijuana plantations were situated. A total of nearly 50 people were killed and bodies were found that had been shot multiple times, tortured and mutilated, typical trademarks of drug-related violence.

The Tijuana Cartel allied themselves with the Gulf Cartel in 2004 and 2005, the main adversary of the Sinaloa Cartel. After the initial fighting in 2004 between the two cartels the Sinaloa Cartel started to attack its rival at their home base, the town of Tijuana on the U.S. border. The majority of clashes between the Sinaloa Cartel and the [Tijuana Cartel](/#actor/799 have taken place in Tijuana and Baja California state since 2005.

The non-state conflict between the Sinaloa Cartel and the [Tijuana Cartel](/#actor/799 was first included in UCDP data in 2004. In January of that year, major clashes took place between the two cartels which resulted in more than 25 battle-related deaths.