Also we had strong, or at least some important comunist/socialist movements led by syndicates and teachers sometimes.
In Guerrero Lucio Cabañas, part of the Poors Party was masacred also for fighting against the landowners and capitalist scum. There was also Ruben Jaramillo, another socialist leader massacred by the army, theh also killed all of his family. The railroad man strikes in the 50's and 60's, the medics strike also in the 50's-60's; and the copra workers strike (copra being the "meat" of a coconut) which ended in a massacre of more than 50 copra workers in Acapulco.
And well, yes, the cumination of all those years of struggle and foghting where ended in the 2 of october massacre, or the Tlatelolco massacre, an event that even now we don't have exact numbers of how many people died, or where killed by the army. A bloody stain in mexican history, one that even that is as tragic as it can get, people seem to forget, specially the latest generations.
And ye, the "Liga Comunista 23 de Septiembre" or Comunist League 23 of september a comunist guerrilla group was exterminated by the army and the political elites of the time.
A known case is Alicia de los Rios, a woman gueriila fighter who never appeared after being taken by the army, or the secret police.
Pretty much the dirty war was a extermination of all comunist policy.
And also a short story: my grandpa was in Tlaxcala when the student movement of 68' was around; he once told me the army entered one of his study groups (he was part of a marxist leninist study group), they were in a mate's house, the army entered with bayonets trying to arrest everyone. Luckily my grandpa escaped through a window and dissapeared a few days, but some of those mates he was around, he never saw them again, probably were taken to a military base or some other shite where they were tortured or just killed.
Oh, and as the other anon said, the CIA where pretty much the ones behind of all of this stupid shite, Gustavo Diaz Ordaz "El Chango" had a codename as a CIA asset, which was LITEMPO if ain't mistaken.