A group of American Muslim high school girls could not enter the kingdom to make a sacred pilgrimage called Umrah to the holy city of Mecca. No, they could not enter Saudi Arabia, even under the supervision of adult female chaperons.

They could only make the journey to Islam's holiest sites accompanied by a male relative, called a mahram. This was tradition, observed since the days of the Prophet Muhammad.

In March, without explanation, the Saudi Embassy reversed its decision. Two days later, a group of 15 students and five women from the all-girl Al-Aqsa School in Bridgeview, Ill., boarded a plane to Jeddah, blazing a trail that they pray will be followed by other girls.

"It was like a visa from God," said Maai Shaker, a student who went on the trip. For the girls, who are anticipating graduation in June, the trip has become the highlight of their senior year.

It's unclear why the Saudis shifted their policy to allow the girls to travel without a male escort. A woman in the visa section of the Saudi Embassy would say only that the girls received a "special permit." It's also not clear whether this was the first time the Saudis waved the requirement. But the situation is unusual.

The girls' trek comes amid a lively debate among Muslim women about their role in Islam and the balance between tradition and modernity, particularly among educated, Western Muslim women. In recent years, they have pushed the envelope, observers say, demanding rights such as equal access to prayer space in mosques that have forced a redefinition of what it means to be a Muslim woman.

What unites the women is social status, said Kecia Ali, an assistant professor of religion at Boston University.

"It's very important to be clear that when we talk about these debates, we're talking about a subset of educated elite Muslim women," Ali said. "The majority (of Muslim women) live in poverty, and poverty does as much to dictate the circumstances of their lives as religion."

Though most Saudi Arabian women do not live in poverty, the kingdom is influenced by conservative Wahhabi clerics whose religious rulings have, among other things, barred women from wearing bras or high heels. As the keeper of Islam's holiest shrines, the country has prided itself on observing traditions that govern the major Hajj pilgrimage and a smaller one, called Umrah, which the girls did.

Many Saudis weren't prepared to encounter 20 unaccompanied Muslim women from America making the Umrah trek, the girls said. Yomna Elsiddig, one of the students, said a bellhop stood dumbfounded in the hotel lobby. "He said, 'Where's the man?'" she recalled. "He was so surprised he didn't know what to do."

Aminah McCloud, a professor of Islamic Studies at DePaul University, said some of the recent strides toward gender equality are a natural outcome of Muslim women searching for ways to blend their religion with American culture, particularly converts who may not have Muslim relatives.

"It can be very much viewed as 'Oh, my God, it's going against religion,'" McCloud said. "I think they view it as trying to practice Islam when maybe their fathers and husbands and brothers couldn't go on the pilgrimage.

"Obviously the Saudis heard the arguments and agreed because they let them in."

In fact, no one at the Saudi Embassy was available to explain why the visas arrived this time.

Khalid Baste, the principal of the Al-Aqsa School and a chaperon on the pilgrimage, said students from the school had been applying for pilgrimage visas for at least 20 years. She remembers applying when she was a student at the school 17 years ago. Each time, the Saudi Embassy informed them that their applications had been denied.

"They said each girl needed a mahram," Baste said, who has made previous pilgrimages accompanied by male relatives. "Or we just got no answer at all."

Some Muslim leaders in Chicago attribute the change of heart to the nature of the Umrah pilgrimage. Unlike the Hajj, the trek to Mecca and Medina that every Muslim strives to make once in a lifetime, Umrah is a mini-pilgrimage that is considered more relaxed, though pilgrims generally observe all the rituals, such as circling the Kaaba, a shrine that Muslims believe was built by the Patriarch Abraham, whom they call Ibrahim.

Without attributing too much significance to this one incident, other Muslims said Saudi Arabia might be feeling pressure to entertain interpretations of Islam that are less strict than those of the kingdom's Wahhabi clerics. As gatekeepers to Islam's holiest sites, they've been able to enforce traditions such as the mahram.

"They've been imposing their doctrine on the rest of the Muslims, and it's very unfair," said Assad Busool, a professor at the American Islamic College in Chicago. "There are a lot of rumblings about this, even in Saudi Arabia, so they must open up."

Whatever the reason, the Saudi decision allowed these senior high school girls to spend spring break on a spiritual journey that some said was all the more special because they could bond uninterrupted by fathers and brothers.

"I think having a man there would have made it a lot less special," said Nadia Ismail, a student.

The girls recounted moments of splendor as they stood before the Kaaba and walked between the hills of Safa and Marwah, re-enacting Hagar's search for water, as described in the Quran. Back in Chicago, like high school girls everywhere, they giggled about their shared experiences. But many also cried as they described the life-transforming journey.

"When you're near it you're so close to God," said Tahanee Ghanayem. "It's almost like a piece of heaven."

The girls said they relished the memories, even if they found humor in some Saudi customs that for these American-born daughters of immigrants appear antiquated and unnecessary. A guardian may have been a good idea when camel-led caravans braved the desert, they said, but not today.

Umrah is a pilgrimage to Mecca performed by Muslims any time of the year. It is sometimes called the "minor pilgrimage." Unlike the Hajj, the major pilgrimage to Mecca that every Muslim strives to make once in a lifetime, the Umrah is not considered obligatory by most schools of Islam.