Exploration refers to the historical practice of discovering remote lands. It is studied by geographers and historians. Two major eras of exploration occurred in human history: one of convergence, and one of divergence. The first, covering most of Homo sapiens history, saw humans moving out of Africa, settling in new lands, and developing distinct cultures in relative isolation. Early explorers settled in Europe and Asia; 14,000 years ago, some crossed the Ice Age land bridge from Siberia to Alaska, and moved southbound to settle in the Americas. For the most part, these cultures were ignorant of each other's existence. The second period of exploration, occurring over the last 10,000 years, saw increased cross-cultural exchange through trade and exploration, and marked a new era of cultura