Americans spend more than half a billion dollars annually on 150 million units of imported Christmas lights. U.S. News & World Report ranks the best Christmas light displays. And ABC’s reality TV show “The Great Christmas Light Fight” recently premiered its 10th season. Christmas lights, in short, are not only ubiquitous but also central to American culture.

But that has not always been the case. The man credited with popularizing Christmas lights in the early 20th century, Albert Sadacca, had never celebrated Christmas. In fact, he was a Jew from the Muslim world.

How Sadacca (1901-1980), his brothers and other Jews from the Ottoman Empire pioneered the Christmas-lights market a century ago reveals a dark side of their story — one shaped by nativism, antisemitism, Islamophobia and labor exploitation. Those forces have scrubbed Sadacca’s Ottoman Jewish background from our understanding of the holiday and the twinkly lights that illuminate it.

Sadacca, his parents and five siblings came from Canakkale, a town across the Sea of Marmara from Istanbul on the Asian side of the Dardanelles. They arrived in the United States between 1907 and 1911, as the Ottoman Empire embarked on a cataclysmic decade of war. They numbered among the 60,000 Jews from the Ottoman Empire — today’s Turkey, Greece, Syria and elsewhere — who arrived during the first quarter of the 20th century. A small group compared with the 2 million Eastern European Jews arriving in the same era, Ottoman Jews flummoxed immigration officials and new neighbors alike. They were largely the descendants of Jews expelled from Spain in 1492 who found refuge in the Ottoman Empire. These Sephardic Jews developed a language known as Ladino that fused Castilian Spanish with Hebrew, Turkish, Greek and Italian — which they wrote in Hebrew letters. Eastern European Jews on the Lower East Side of New York could not imagine Jews who did not speak Yiddish. Instead, Sephardic Jews gravitated to Puerto Rican communities in Harlem because of the similarity of their languages.

According to the eugenics-inspired racial classifications of the era, were these newcomers “Hebrews”? Or “Turks”? Regardless, immigration authorities considered them part of an “invasion” from “Western Asiatic countries” that threatened to undermine the White, Protestant character of the country. Some became ensnarled by immigration laws that excluded Muslims by barring those who practiced polygamy or came from polygamous societies. Debates raged in the press and the courts over whether those from the Ottoman Empire ought to be eligible for naturalization — a privilege available to those deemed “White” by law, always a contested category.

Ottoman Jews — who called themselves Turkinos in Ladino — sought comfort among their own. They established cafes, mutual aid societies, synagogues, religious schools, Ladino newspapers, theater troupes and social and political organizations in New York and in cities across the country, from Atlanta to Indianapolis, Los Angeles and Seattle. In New York, some found work as coatroom attendants, bootblacks, postcard peddlers or theater concessionaires. Many worked in the garment industry or in battery, flashlight and lightbulb factories.