Mexican muralism was a mural painting movement that started in the 1920s, with social and political messages as part of efforts to reunify the country under the post Mexican Revolution government. It was headed by “the big three” painters, Diego Rivera, José Clemente Orozco and David Alfaro Siqueiros. (https://en.wikipedia.org/wiki/Mexican_muralism)

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«From 1910 to 1920 civil war ravaged the nation as citizens revolted against dictator Porfirio Díaz. At the heart of the Revolution was the belief—itself revolutionary—that the land should be in the hands of laborers, the very people who worked it. This demand for agrarian reform signaled a new age in Mexican society: issues concerning the popular masses—universal public education and health care, expanded civil liberties—were at the forefront of government policy. (...) At the end of the Revolution the government commissioned artists to create art that could educate the mostly illiterate masses about Mexican history. (...) The muralists developed an iconography featuring atypical, non-European heroes from the nation’s illustrious past, present, and future—Aztec warriors battling the Spanish, humble peasants fighting in the Revolution, common laborers of Mexico City, and the mixed-race people who will forge the next great epoch, like in Siqueiros’ UNAM mural» (https://www.khanacademy.org/humanities/art-1010/art-between-wars/latin-american-modernism1/a/mexican-muralism-los-tres-grandes-david-alfaro-siqueiros-diego-rivera-and-jos-clemente-orozco)