It's horrifying to watch: Egyptian soldiers viciously beating a woman, then peeling back her abaya to expose her torso and bra, before a soldier delivers one last stomp to her chest.

The image from a Dec. 17 crackdown on protesters in Cairo's Tahrir Square, circulated over the Internet and on news broadcasts globally, helped sparked a Dec. 20 protest march through central Cairo by thousands of outraged women. Other women had been attacked and stripped that day in what was clearly an attempt by soldiers to humiliate female protesters.

What happens in the video isn't entirely surprising. Women in Egypt and most parts of the Arab world are frequently subjected to violence and harassment, in public spaces and at home. In most Arab countries, there are no laws protecting women from domestic abuse, spousal rape or even murder if she has "dishonored" the family. And a woman's testimony is worth only half that of a man's. Not surprisingly, women tend not to report being violated to authorities.

As a result, there are no reliable statistics for abuse of Arab women and girls. Surveys, however, give a sense of what they face. A 2008 poll by the Egyptian Center for Women's Rights found that 83 percent of Egyptian women had been sexually harassed and that half faced harassment every day. According to a 2007 Qatar University study, 63 percent of female students had been victims of physical abuse. A 2009 Palestinian Women's Information and Media Center survey of women in the Gaza Strip showed that 52 percent faced regular physical violence; for 14 percent, that included sexual violence.

These studies are cited by the U.S. Department of State in its 2010 reports on human rights in those jurisdictions. In a fourth survey, cited in a report of the department's Middle East Partnership Initiative and conducted by the Athar Foundation for Development and Impact Institute, a stunning 99% of Yemeni women and girls said they encountered sexual harassment on Yemen's streets.

As a Jerusalem-based reporter throughout the 1990s, I found it difficult to find sufficient numbers of Palestinian women to interview for my stories. Rarely in positions of authority and underrepresented in the streets and shops, they could mainly be found in their homes. Even there, they often retreated to back rooms. At first, I assumed the rules were enforced with words and looks. In time I learned of beatings, rapes and killings.

It's been said often enough that Arab countries can't progress or compete in the global economy when half their population is cloistered. Yet Arab women can't contribute to public life if they are too frightened to enter public spaces. By banding together, the women marchers in Cairo have thrown off their fear. Maybe their Arab sisters elsewhere will follow their example.

(Lisa Beyer is a member of the Bloomberg View editorial board.)