NAJRAN, Saudi Arabia  Among the ruins on the edge of this ancient oasis city are deep trenches littered with bones. That, local people say, is all that remains of one of the great atrocities of antiquity, when thousands of Christians were herded into pits here and burned to death by a Jewish tyrant after they refused to renounce their faith.

The massacre, which took place in about A.D. 523, is partly shadowed by myth and largely unknown to the outside world. But it has become central to the identity of the people now living here, who mostly belong to the minority Ismaili sect of Islam. The Ismailis, widely reviled as heretics by Sunni Muslims both here and abroad, see the oppressed Christians of ancient Najran as their literal and figurative ancestors in a continuing struggle for recognition by the Saudi state.

“This story means so much to us,” said Ali al-Hattab, a 31-year-old hospital worker and graduate student. “Our life and our struggle today comes from those martyrs who gave their lives for their beliefs.”

The Saudi government does not take kindly to this analogy. Part of the site where the Christians are said to have been killed  including charred remnants from the fires  was buried and paved over years ago. In a small museum next to the ruins that is dedicated to the city’s ancient history, there is only one brief reference to the massacre. In part, this is a reflection of the deep hostility among Saudi conservatives toward any artifacts that predate the birth of Islam in the seventh century.