EL PASO, Texas (AP) — More than 4,000 archaeological artifacts looted from Mexico and seized in the U.S. have been returned to Mexican authorities in what experts say is one of the largest such repatriations between the countries.

The items returned Thursday mostly date from before European explorers landed in North America and include items from hunter-gatherers in pre-Columbian northern Mexico, such as stones used to grind corn, statues, figurines and copper hatchets, said Pedro Sanchez, president of the National Archaeological Council of Mexico.

U.S. Immigration and Customs Enforcement agents seized the relics in El Paso, Phoenix, Chicago, Denver, San Diego and San Antonio, though most of the artifacts — including items traced to a 2008 theft from a museum in Mexico — turned up in Fort Stockton, a Texas town about 230 miles southeast of El Paso.