2001 - Joaquin "Shorty" Guzman escapes from a Mexican prison in a laundry van. Guzman, Mexico's most-wanted drug lord, then builds a coalition of drug gangs from the western state of Sinaloa and vows to take control of Mexico's vast drug trade.
2002 - Police weaken the Tijuana Cartel by killing drug boss Ramon Arellano Felix and arresting one of his brothers.
2003 - Mexican soldiers capture Osiel Cardenas, leader of the Gulf Cartel based in eastern Mexico, after a shootout between troops and gunmen in the border city of Matamoros.
2004 - Trying to take advantage of Cardenas' arrest, Guzman sends well-armed enforcers to border cities south of Texas to take over Gulf cartel smuggling routes. Heavy fighting breaks out before Guzman's fighters are eventually repelled.
2005 - Guzman seeks control of the border city of Tijuana and trafficking routes into California. Violence escalates across Mexico and about 1,500 people are killed over the course of the year.
2006 - Killings spread to the resort of Acapulco, the industrial city of Monterrey, and to Michoacan in western Mexico, the home state of Felipe Calderon. After taking over as president on December 1, Calderon immediately deploys troops and federal police to stem the violence.
September - La Familia, a pseudo-religious drug gang, tosses a bag filled with severed heads onto the dance floor of a night club in Uruapan, in Michoacan state.
2007 - Calderon extradites Gulf Cartel leader Cardenas to the United States and announces a historic 23-tonne cocaine seizure. US President George W Bush pledges $1.4bn in drug-fighting gear and training for Mexico and Central America. Violence escalates and more than 3,000 people are killed over the course of the year.
2008 - Guzman's hitmen take on the Juarez Cartel in the northern border city of Ciudad Juarez, across from El Paso, Texas, which quickly becomes the drug war's bloodiest flashpoint. Drug violence kills around 6,300 people across Mexico over the year.
August - Hundreds of thousands join marches across Mexico to protest against increasingly brutal drugs-related violence.
2009 - Calderon sends 10,000 more troops to Ciudad Juarez but the killings continue. Violence spills over the border into Arizona. US President Barack Obama visits Mexico and vows to clamp down on smuggled guns, but the annual drug war death toll soars above 7,000. In January, gunmen hurl a grenade at the offices of the broadcaster Televisa in Monterrey, as violence against journalists increases.
In December, an elite navy squad tracks down and kills drug lord Arturo Beltran Leyva, head of the cartel of the same name and one of Mexico's most-wanted traffickers. Six bodyguards also die in the raid on a luxury apartment in the city of Cuernavaca, near the capital.
2010 - In January, police capture drug kingpin Teodoro "El Teo" Garcia Simental, known for having rivals tortured, killed and then dissolved in acid. But the cartels grow more brazen, killing three people linked to the US consulate in Ciudad Juarez and setting off car bombs. Mass killings at drug rehabilitation centers and parties become common and mayors and local officials are assassinated.
February - The Zetas, formed by US-trained counter-narcotics operatives, split from the Gulf Cartel, for whom they were working as enforcers. This split leads to far worse violence in Mexico's northeast.
June - A candidate for governor in Tamaulipas state is gunned down while campaigning.
August - Suspected members of the Zetas Cartel massacre 72 migrants at a ranch near San Fernando, south of the Texas border.
August - Police arrest Edgar Valadez, known as "La Barbie", a US-born kingpin from the Beltran Leyva cartel. US authorities had placed a $2m bounty on his head.
September - Thirty-five bodies are dumped at a busy intersection in coastal city of Veracruz, announcing the arrival of a new cartel, the so-called "mata Zetas" or "Zetas Killers". Some analysts suggest this marks the "paramilitarisation" of Mexico's drug war.
December - WikiLeaks cables show that the US ambassador is concerned about the ability of Mexico's security forces to handle threats from organised crime.
December - Nazario Moreno Gonzalez, known as "El Chayo" or "the doctor", a leader of La Famila Cartel, is killed in a gun battle with police.
2011 - In January, more than 150 inmates escape from a prison in Nuevo Laredo in the largest prison break in Mexican history.
April - Anti-violence protesters take to the streets again with the poet Javier Sicilia, whose son was murdered in March, assuming a leading role. Dozens of mass graves are found in Tamaulipas, containing 193 bodies.
August - An attack at a casino in Monterrey, the country's wealthiest city, leaves 52 people dead after gunmen set the building on fire.
November - Toney Tormenta, a leader of the Gulf Cartel, is killed by security forces in northern Mexico, sparking violence and an exodus of the local population.
2012 - In January, police in the northern city of Torreon find the severed heads of five people.
May - Security forces in Nuevo Laredo find the bodies of nine people hanging from a bridge.
May - Three photojournalists are killed in Veracruz, intensifying the atmosphere of self-censorship in one of the world's most dangerous countries for reporters.
August - Spain arrests four members of the Sinaloa cartel, including the cousin of Joaquin Archivaldo Guzman, known as El Chapo. The four men were arrested near their hotels in the capital Madrid, the ministry said in a statement.
September - Mexico arrests Jorge Eduardo Costilla Sanchez, the leader of the Gulf drug cartel, which controls some of the most valuable and violently contested smuggling routes along the US border.
September - Mexican navy arrests a man believed to be Zetas boss Ivan Velazquez, also known as "El Taliban" or "Z-50," in central Mexico, boosting outgoing President Felipe Calderon's efforts to crack down on the violent cartels.
October - Top Zetas drug cartel leader Heriberto Lazcano was apparently killed in a firefight with marines in the northern border state of Coahuila. The navy said there was strong evidence the body of one of two men killed in the shootout was Lazcano, known as "El Lazca" but it added that more forensics tests would have to be carried out to confirm the identification.