Gauchos, the legendary Argentine horsemen who lived by their knives and their wits on the open plains called the Pampa, learned Yiddish. Maximo Yagupsky, a 75-year-old Argentine Jewish journalist who grew up in an immigrant colony on the Pampa, told an inteviewer some years ago about the gaucho Manuel del Pozo, who used to listen every Friday as Yagupsky's father said the Sabbath blessing.

One Friday, as Yagupsky told it, his father was awy and the family had to tell del Pozo that the blessing would not be said. "Give me a cup of wine," said del Pozo. "We gave him a cup," said Yagupsky, "and he said the entire Sabbath blessing in Hebrew from memory. And when he left, he told us 'gut shabes '" -- "good Sabbath" in Yiddish.

For 300 years, according to Judith Laiken Elkins's "Jews of the Latin American Republics," people of Jewish descent had filtered into the colonies of South America -- many of them newly converted Catholics who were known as "conversos " and lived with stigma that rose and fell with the times.

But the Jews who came to Argentia, in by far the largest Jewish immigration to Latin America, did not arrive en masse until the turn of the century, when ocean ships began carrying them to the wild, raw land of the Pampa. A Jewish philanthropist was responsible for much of the colonization -- he had a vision of Jews founding rich agricultural settlements.

"It was the gaucho," Elkin writes, "who taught Jewish immigrants how to ride, how to herd cattle, how to shelter against the elements, how to shoot. In the end, the gaucho taught the colonist his own primitive methods of agriculture -- a rude twist to the Argentine hopes that European immigrants would educate the gaucho to more advanced techniques."

In the end most of the colonists migrated to the cities, escaping bad crop years and seeking education. There are still heavily Jewish settlements in the provinces northwest of Buenos Aires, but most of the country's Jews live in the capital.

In their neighborhoods the faces you pass are not the sleek-haired Italians who seem to fill so much of Buenos Aires. These are Eastern European faces -- Polish, Bulgarian, Russian. So many of their parents and grandparents immigrated from Russia that the nasty Argentine slang for "Jew" is "russo." The city has 40 Jewish primary schools, 10 Jewish high schools, a Yiddish daily paper, a Jewish weekly paper, 55 synagogues and a rabbinical seminary run by Marshall Meyer, an American rabbi who has lived in Buenos Aires for 22 years.

If you had dropped by Temple Bet El on a recent Friday night, you would have heard his congregation singing, and in front a dark-haired young man lifting his voice to lead the welcoming-in of the Sabbath.