Complex sentence: One of the key factors responsible for this military coup was the political mobilization of the rural lower classes, which threatend to undermine a tenet central to the government led modernization, the exclusion of the lower rural classes from citizenship.
Split into simpler sentences: One of the key factors responsible for this military coup was the political mobilization of the rural lower classes. This threatend to undermine a tenet central to the government led modernization, the exclusion of the lower rural classes from citizenship.