Along the historic El Camino Real de Tierra Adentro (The Royal Inland Road), there were approximately 20 to 21 distinct Pueblo communities in the northern province of Nuevo México (modern-day New Mexico). These ancestral and contemporary Pueblo sites were critical nodes along the 1,600-mile trade route that stretched from Mexico City to Ohkay Owingeh. Major pueblos directly on or very near the trail included Isleta, Santo Domingo (Kewa), San Felipe, Sandia, and San Juan (Ohkay Owingeh). The Spanish utilized these existing indigenous settlements as points of "reducción" (concentration), trade hubs, and sources of labor and supplies. Today, many of these pueblos remain vibrant, sovereign nations along the Rio Grande valley. The trail is a UNESCO World Heritage site and a National Historic Trail, commemorating the complex 300-year history of interaction between Spanish colonists and the Pueblo peoples. While the total number of "sites" on the trail exceeds 60, the core group of living Pueblos that provided the cultural and logistical anchor for the northern end of the route remains around 20.