Although Spanish explorers visited the Colorado region and traded with
Native Americans, they never settled there.

The first Europeans to penetrate the area now known as Colorado were Spanish explorers. As a result, Spanish place names permeate the area - Sangre de Cristo (Spanish for "Blood of Christ"), Sierra Mojada (Spanish for "Wet Mountains"), and Colorado itself (Spanish for "red"). Juan Archuleta (1664) and Juan Ulibarri (1706) were the first Spanish explorers to enter Colorado. To the Spanish in Taos and Santa Fe, the region to the north was regarded as frontier inhabited by hostile Indians.

After the explorations of Joliet (1673) and LaSalle (1682), Spanish fears of French incursions into Colorado were awakened. Now, the region to the north became a disputed frontier. In 1706, Captain Juan de Ulibarri led 140 soldiers, settlers, and Indians northward from Taos, New Mexico along the Wet Mountains to the Arkansas River at Fountain Creek in search of invading Frenchmen and hostile Indians.