Leon Trotsky, Fidel Castro, Augusto César Sandino.

All spent time in Mexico, a country that's welcomed waves of political exiles over the decades and is now paying homage to some of the most famous of them.

In 1929, while he fighting a U.S. military occupation of Nicaragua, Sandino received permission to shelter in Mexico from President Emilio Portes Gil. In 1937, Trotsky came to Mexico using painter Diego Rivera as a reference. In 1955, a Cuban by the name of Fidel Castro entered Mexico as a tourist, telling authorities he was on vacation.

The dates and facts are recorded in migration records preserved in Mexico's historic archives and put on display to commemorate the 20th anniversary of the country's National Institute of Migration.

"These are very valuable documents, and they're part of the national patrimony," said Fernanda García Villalobos, director-general of regulation and archives for the institute.

The yellowed immigration documents of 16 notable visitors can be seen at the institute's offices until the end of November. Some are machine-stamped, others filled out by hand. Some include photos, such as one showing a young Castro with a mustache but not yet a beard. Another shows Trotsky, with the white beard, mustache and round glasses that he had until his death at the hands of an assassin in Mexico.

It's a tiny sample of the nearly 500,000 records of foreigners in the migration institute's files. García said the institute hoped to put on a larger exhibit in the future.

While the documents only record the foreigners' entries into the country, for García the documents are "an important part of the story of these people," including some, such as Spanish surrealist painter Remedios Varo, who ended up taking Mexican citizenship.

Castro used his time in Mexico to organize the group of rebels who took a boat to Cuba in 1956 to launch the rebellion against dictator Fulgencio Batista.

On that, the documents are silent.

"We don't have any information on that," García said. Officially, "he was only on vacation, he came as a tourist."

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