Greedy oligarchies have been a major problem for El Salvador's masses since the Pipil Indians unsuccessfully tried to resist the Spanish in the 1520s. After independence from Spain, elitist natives dominated El Salvador's economy, and liberals and conservatives vied for political power. El Salvador's contemporary revolutionaries trace their lineage to Agustin Farabundo Marti. During the mid-1920s, Martí participated in a literary circle in San Salvador and worked with a secret Communist youth group. To combat the US-supported Salvadoran military, Carpio resorted to armed struggle and mass political organizing. The cosmopolitan Roque Dalton had a talent for teaching, for conveying his political ideas, which appeared in over a dozen books of poetry and political essays. Rafael Menjivar found that modernization in El Salvador caused what economist Andre Gunder Frank called "the development of underdevelopment," which enabled a small sector of society to benefit at the expense of the majority, produced financial and public disequilibrium, and increased external debt.