The brilliant civilization of the Incas originated in Peru. Their empire dominated the Andes by the end of the 1400s. Pizarro's arrival on behalf of Spain in 1532 hastened the end of the Incas, although their subjugation would not be complete until nearly 40 years later. The rich natural resources of Peru, specifically gold and other metals, made it especially attractive to the Spanish and for the next 200 years, Lima was the center of the region's wealth and power. In 1821, Simon Bolivar and Jose de San Martin defeated the royalist forces and Peru was independent, though in the next four decades, power changed hands 35 times and the country went through more than 15 constitutions. For over fifty years (from the 1930s till the 1980s) there was great hostility between the armed forces and the supporters of Peru's most important political party, the so-called Apristas. Consequently, APRA was prevented from taking power until 1985. Peru's problems exacerbated in the 1980s with the rise of the Maoist 'Shining Path' guerrillas, continuing into the '90s.