Encounter, trade, and exchange- among distant groups as well as neighboring ones- were fundamental to the development of art and culture in ancient America. After Columbus's historic voyage of 1492, successive waves of intrusion brought new kinds of foreigners onto the American landscape-ones whose weapons discharged thunder, and who possessed different trade goods and artistic styles, as well as rigid ideas about religion and social hierarchy. In the Southwest they came overland, on foot and on horseback from what is today Mexico; in Alaska, they arrived first from Russia in boats; and in the east they arrived in multiple migrations, some from Mexico, and some directly from Europe. One and a half million newcomers arrived against their will, from Africa. The rate and level of cultural encounter would accelerate in a way previously unimagined in the Americas. All of the land's inhabitants-aboriginal and newcomer-and their visual cultures would be changed irrevocably by the next five centuries of encounter.