On Mountain Trails is a memoir in two sections about living in the Sacred Valley of the Incas during the 1970s. The first, Pavanne for Paucartambo, chronicles two trips on horseback to Paucartambo with their unforeseen consequences. Journey to the Sacred Plane relates the author's 500-kilometre journey with two horses to Vilcabamba, where for thirty-six years the Incas had found sanctuary from the Spanish conquerors in the fastness of this wild and rugged land, ruling over an independent kingdom in an uneasy truce that alternated between appeasement and rebellion. Tupac Amaru’s execution ended the Inca line forever, yet in the ruins of Vitcos, the Inca’s last capital, and in Vilcabamba the Old, his final refuge, he left behind the traces of a valiant, if hopeless stand against a merciless enemy. How had the Inca, with only a small group of followers, managed to survive against all odds, relentlessly pursued by the 16th century’s most powerful military machine? Was it the difficulty of the terrain that permitted the Indians to live unimpeded in isolation? Or was it a superior military strategy that kept the conquistadores from their door?