Alsina's trench
La muralla criolla (original)
Documentary film about the "zanja de Alsina", a long trench dug in the Argentinian Pampa in 1876 as way to separate the "civilized" from the "barbarians" during the massacre of indigenous peoples known as "campaña del desierto".
Starring Osvaldo Bayer, Marcelo Valko, Juan José Estévez, Gastón Partarrieu, Eduardo Hiriart, Alberto Orga, Jorgelina Walter, Armando Nervi, Federico Aimetta, Sebastián Díaz
Watch "Alsina's trench" on Amazon released in 2017. It's a documentary and history movie, and has a rating of 6.4 out of 10 from Imdb which is usually fine for this kind of movie, and is currently only available for purchase or rent.