It proves tricky to extract a straight answer from the Yazidis when it comes to what, exactly, defines their sect.
Take their fierce prohibition against eating lettuce.
A man who teaches the Yazidi equivalent of Sunday school avoids the simple kind of explanation found in encyclopedias — that the process of fusing a smattering of faiths including Zoroastrianism, Christianity and Islam left the origins of many Yazidi practices obscure.
Instead, the teacher, Falah Hassan Juma, links the sect's lettuceless state to its long history of persecution by Muslims and Christians.
The caliphs of the Ottoman Empire carried out no fewer than 72 massacres against the Yazidis in the 18th and 19th centuries alone, he explained, with the faithful slain by the thousands in the lettuce fields then dotting northeastern Iraq.
Watching the blood of innocents gush into the greens prompted a lasting aversion to the vegetable, Mr. Juma said, speaking with what sounded like real authority.
That is not quite right, a sect elder spelled out later. Indeed Yazidis suffered persecution, he said, such that one ruthless potentate who controlled the nearby splendid city of Mosul in the 13th century ordered an early Yazidi saint executed. The enthusiastic crowd then pelted the corpse with heads of lettuce. There have been sanctions against salad ever since, the elder intoned.
Ask a government-issued minder from Mosul, a Muslim, and he mutters about how Yazidis believe that the local romaine houses Lucifer, whom he says they worship, so they refuse to chop the heads off the roots.
In the end, the art of dissembling about their religion, perhaps the strongest Yazidi tradition, triumphs. No clear explanation emerges.
Armies and empires have crisscrossed Iraq for thousands of years, leaving the remnants of spectacular civilizations scattered from the Persian Gulf to the mountains of northern Kurdistan.
Peoples who seem to date from another time and another place — Mandeans who worship John the Baptist, Assyrians, Turkmen — still inhabit forgotten pockets, caught in an eddy as history swirled on.
The fact that Yazidis have long clung to their microreligion amid far larger concentrations of Christians and Muslims testifies to the ferocity of belief in this region. Indeed, its agglomeration of peoples and faiths is one reason Iraq is considered a fractious place, difficult to govern.
The village of Bashiqa, home to 5,000 people, sits where the Mosul plain meets the plump foothills of the Maklub Mountains. Its Chaldean Catholic church, mosque and Yazidi temple sit within hailing distance of each other.
Surrounding olive groves produce the sacred oil for Yazidi temple lanterns, and distinctive, conical Yazidi tombs dominate the hills. The metal ball topping the tall skinny dome of the pale sandstone tombs represents the sun, and 12 vertical stone ridges radiating down from the ball represent its hallowed rays and the hours of the day.
The Yazidis, who are ethnically Kurds, maintain one of the most eclectic of faiths.
They have adopted Christian rituals like baptism and a smattering of practices from Islam ranging from circumcision to removal of their shoes inside their temples. The importance of fire as a divine manifestation comes from Zoroastrianism, the ancient Persian faith that forms the core of Yazidi beliefs. Indeed their very name is likely taken from an old Persian word for angel.
The veneration of their saints' tombs means few Yazidis have ever wandered far from their Iraqi roots, although there are branches in Turkey, Syria, Iran, the Caucasus and, because of modern migrations, Germany. Estimates on their numbers swing wildly, but are generally put around 300,000 in Iraq.
Yazidis venerate Sheik Adi bin Musafir, a 12th-century Lebanese-born Arab mystic whose tomb, in Lalish in northern Iraq, is their main place of pilgrimage. They say Sheik Adi revived a faith dating back to Adam.
The sect lacks any written text, which helps account for the tall tale aspect of explaining its tenets. Their religious hierarchy is topped by a prince. His title is hereditary, and he can marry only from an upper caste of some 300 families.
Allegations of satanic worship stem from the central figure among the seven angels they worship. Yazidis consider Ta'us, or the Peacock Angel, to be the devil, but worthy of veneration as one of God's creatures who repented and should be appeased to avert his wrath. His tears on his repentance are said to have doused the flames of hell, putting it permanently out of business.
Yazidis pray three times a day, at dawn, midday and sunset, facing the direction of the sun each time. "The sun is very holy to us," said Walid Abu Khudur, the stocky, bearded guardian of the temple built in honor of a holy man here. "It is like the eye of God, so we pray toward it."
Yazidi elders do worry about their dwindling numbers, since Iraq's desperate economic conditions have pushed the young to emigrate.
"The young want a better life," said Prince Tahseen Sayigh Aly, the sect's leader, sitting in a gloomy room dominated by a life-size picture of President Saddam Hussein propped up in the corner. "Of course we are worried about disappearing, especially since the young cannot marry outside the faith."
Under the secularism of the Baath Party ruling Iraq, all religions are tolerated.
If the Yazidis are tolerated, they are not exactly loved. A Muslim from Baghdad visiting the Yazidis for the first time refuses all offers of tea and coffee lest it be somehow tainted. He shakes his head at the various explanations of the faith, believing that the Yazidis make it up wholesale.
One Yazidi mentions that wearing blue is banned during religious festivals. The first explanation offered suggests that blue is the sole province of the Peacock Angel. But it also seems that one of the Turkish armies who killed some 100,000 Yazidis in 1831 was outfitted in blue, and ever since .