In 1839, the Muslims in Persia instituted a pogrom against the Jews in Mashad. As a result, the hundreds of Jewish families who lived there were given a choice of conversion or death. Many chose to outwardly convert, but they kept their Judaism not only individually but also collectively, maintaining what is considered a remarkably close-knit community even today as they are spread throughout the world.
Their story is not well-known, and even on the Internet it is not easy to find out details. And it is important to know that while Jews have lived in Persia relatively peacefully for a long time, the Muslim attitude towards Jews before Zionism was not always as benign as some would have you believe.
Cross-posted to Palestine Post-ings.