A Mayan urn, made between 900 and 1600 AD, is returning to Mexico after spending more than 50 years at a college in the United States.
The urn, considered to be of high historical value, has been housed at Albion College, Michigan, since 1969.
The Mexican foreign ministry said the urn would now be taken to the Museo de los Altos in Chiapas.
The artefact will be displayed alongside a twin urn that is on show at the museum.
"The recovery of this Mayan urn and reunification with its twin artefact represent an act of great importance for Mexico and its historical heritage," the ministry said in a statement.
The urn, from the archaeological site Laguna Pethá in Chiapas, "has a value intrinsically linked to the history and context of its peoples of origin", it added.
Officials from Albion College and the Consulate of Mexico in Detroit signed the agreement on Tuesday.
"The actual definition [of repatriation] is to return someone or something to their own country," Elizabeth Palmer, head of the Albion College Archives, told the Albion Pleiad.
"Recognising that most pieces of history belong to a specific culture, to a specific country, a specific area and that area, that country should be the rightful owners of whatever object it might be."
The Mayan urn was donated to Albion College Archives by alumnus Marvin Vann in 2003, the Pleiad reported.
It said he had made "personal expeditions" to Mexico and also left the college many other documents and papers.
Ms Palmer said: "Everything else is very legitimate. It's just this urn that is problematic."
In their time, the Mayans ruled large stretches of territory in what is now southern Mexico, Guatemala, Belize and Honduras.