During the 1830s, the major trading center on the southern Plains was Bent's Fort, an American trading post on the Arkansas River in southeast Colorado. Although married to a Cheyenne woman, William Bent also traded with Kiowa and Yamparika, and became tired of the aggravation of keeping them apart when they came to trade. At his suggestion, the Cheyenne and Arapaho decided to meet with their adversaries, and a lasting peace was arranged between them. The "Great Peace of 1840", a landmark of southern Plains diplomacy, was cemented by the gift of large numbers of Yamparika and Kiowa horses to the Cheyenne and Arapaho.