Because of the diverse cultures and geography, the Inca allowed many areas of the empire to be governed under the control of local leaders, who were watched and monitored by Inca officials. This vast area of land varied greatly in cultures and in climate. In less than a century, the Inca had expanded their empire from about 400,000 km 2 (150,000 sq mi) in 1448 to 1,800,000 km 2 (690,000 sq mi) in 1528, just before the arrival of the Spanish. Extending southward from the Ancomayo, which is now known as the Patía River, in southern present-day Colombia to the Maule River in what would later be known as Chile, and eastward from the Pacific Ocean to the edge of the Amazonian jungles, it covered some of the most mountainous terrains on Earth. When the Spanish arrived at the borders of the Inca Empire in 1528, it spanned a considerable area and was by far the largest of the four grand pre-Columbian civilizations. The conquest of the Inca Empire (called "Tahuantinsuyu" or "Tawantinsuyu" in Quechua, meaning "Realm of the Four Parts"), led to spin-off campaigns into present-day Chile and Colombia, as well as expeditions towards the Amazon Basin. It was the first step in a long campaign that took decades of fighting but ended in Spanish victory in 1572 and colonization of the region as the Viceroyalty of Peru. After years of preliminary exploration and military skirmishes, 168 Spanish soldiers under conquistador Francisco Pizarro, his brothers, and their indigenous allies captured the Sapa Inca Atahualpa in the 1532 Battle of Cajamarca. The Spanish conquest of the Inca Empire, also known as the Conquest of Peru, was one of the most important campaigns in the Spanish colonization of the Americas. Banda Oriental and Rio Grande do Sul (1762–63).Iberian Peninsula and South America (1762–63).