In 1492, as every American schoolchild knows, King Ferdinand and Queen Isabella of Spain sent Christopher Columbus on a fateful voyage to India that ended up changing the history of the world.
But 1492 was also a dolorous year in the history of European Jewry. On March 31, 1492, Spain's hard-line Catholic rulers issued a decree offering Jews in the country a terrible choice: Convert to Christianity or get out. Many fled, giving rise to a worldwide diaspora of "Sephardic" Jews, after the Hebrew word for Spain.
More than 500 years later, descendants of those Jews now have a chance to return to their ancestral homeland, after the Spanish government's approval in June of a much-discussed proposal allowing Sephardim to apply for Spanish nationality. The law took effect Thursday.
The history: Until their expulsion, Jews lived in Spain in an uneasy but mostly peaceful coexistence with their Christian and Muslim neighbors for hundreds of years.
But toward the end of the 15th century, Spain's rulers became obsessed with Catholic conformity. They launched the infamous Inquisition in 1481 and, a decade later, signed the Alhambra Decree, which accused Jews of trying to turn Christians "to their own wicked belief and conviction" and ordering them to convert or leave.
While some stayed behind as conversos, or converts, others went into exile across Europe, North Africa and the Middle East.
The new law: First introduced in 2012, the bill that was passed in June allows anyone who can prove his or her descent from Sephardic Jews and who can show a "special link" to Spain to apply for Spanish nationality.
The government in Madrid describes the measure as atonement for the "historic mistake" of the Jews' expulsion. In 1992, the 500th anniversary year of the Alhambra Decree, King Juan Carlos I promised visiting Israeli President Chaim Herzog that "never again will hate and intolerance provoke desolation and exile."
Spain has previously offered some Sephardic Jews the opportunity to apply for citizenship but required that they give up their current nationalities. The new law does not include that requirement.
Who's affected: Estimates vary, but up to 3.5 million Jews trace their lineage to Spain. The highest concentration of Sephardic Jews is in Israel, though many live in countries such as Argentina and Turkey. (Spain is presently home to about 50,000 observant Jews.)
You don't have to be Jewish to be eligible to apply for Spanish citizenship under the law – only descended from Sephardic Jews. Although no one can predict how many people will apply, a Spanish consular official in Tel Aviv told the Madrid-based newspaper El Pais that "there is great expectation. We get calls every day from people asking for information and guidance."
There is also no saying how many people who succeed in acquiring Spanish citizenship would actually move to Spain or just keep a Spanish passport on the side, either out of sentimental reasons, for convenience in traveling around Europe or as a backup in case things in their current home countries go bad.
How it works: Applicants have three years, starting Thursday, to submit their petitions.
Proving Spanish heritage and "special link" to Spain will probably be the hardest part. Rabbinical certification of Sephardic descent is one possibility. Other markers include knowledge and use of Ladino, the old Spanish dialect spoken by Sephardim, or a surname indicating Sephardic or Spanish ancestry, such as Toledano, meaning a person from Toledo.
Proof of a special link to Spain includes past study of Spanish history and culture, doing business in Spain and involvement in conservation of Sephardic culture.