In this undated image taken from video distributed Aug. 14, 2016, an alleged Boko Haram soldier standing in front of a group of girls alleged to be some of the 276 abducted Chibok schoolgirls held since April 2014, in an unknown location. (Militant video/Site Institute/AP)

Although widely understood as the Islamist terrorists that they are, Boko Haram insurgents in the borderlands between Cameroon and Nigeria are also slave raiders — at least that’s what many local residents call them. And there’s good reason to use that term. In many striking ways, Boko Haram’s raids for “wives” parallel the slave raids of a century ago.

Thinking about Boko Haram as slave raiders, complete with a history in the semi-lawless borderlands, might change how policymakers approach this group and similar insurgencies across West Africa.

Boko Haram’s activities echo those of earlier smugglers, Islamist militants, and slave raiders

Boko Haram began in 2002-2004 in Maiduguri, the largest city in northeastern Nigeria, as an Islamist movement in which young men from prominent families and jobless youths rejected any engagement with the Nigerian state. They described the duties of citizenship as taghut, “idol-worship.”

Despite its urban origins, Boko Haram has always based itself in the area’s borderlands, far from the cities, and carried out attacks from those border zones. In particular, Boko Haram has based itself in the Mandara Mountains that straddle the border between far northern Cameroon and Nigeria. The mountains are steep, rocky and heavily populated, giving Boko Haram strong defensive positions. In this area, one of the last strongholds of the insurgency today, I have worked as an archaeologist since the 1980s.

Boko Haram leaders think that in retreating to borderlands, they are following Islamist militant traditions of flight into exile while rebelling against corrupt governments. In addition, the frontier zone between Nigeria and Cameroon offers a convenient cross-border escape route from security forces. For centuries, smugglers and bandits have taken refuge here on the borders, hoping to profit from illegal — but widely recognized and tolerated — activities in different states. Boko Haram continues in that tradition as well.

As I show in my new book, slave traders most often raided West Africa’s frontier zones. Pre-colonial rulers supported themselves in part from the profits of owning and selling people. They preferred to capture slaves in areas just beyond their borders rather than within their states. A ruler who enslaved his own citizens did nothing for his popularity, or his life span. People who lived on the borders of pre-colonial states endured violence and danger: some might gain wealth from slave-raiding, but most were farmers and herders who wanted only to live their lives undisturbed by such attacks.

The last major slave raids in the region took place from 1912 to 1920. They were directed by Hamman Yaji, a Fulani Muslim chief living in the Nigerian town of Madagali. Hamman Yaji kept a diary which, extraordinarily, survived and has been published in English. Before he was deposed by the British — on suspicion of being an Islamist extremist, not for slave raiding — Hamman Yaji terrorized Mandara populations. His diary is full of accounts of the capture of young women, the preferred targets of those raids. The British had officially ended slave markets in northern Nigeria a decade before, but Hamman Yaji gave away many enslaved women to his followers, as prizes and incentives for continued loyalty.

Roughly a century later, in 2014 Boko Haram kidnapped more than 250 teenage girls in Chibok, 50 miles from Hamman Yaji’s old base in Madagali. Abubakar Shekau, Boko Haram’s leader, in one video threatened to “sell” those girls “in the marketplace” — even though, now as a century ago, no such market exists. Instead, like Hamman Yaji, Boko Haram leaders dole out captured women as rewards to their followers. Many young women who escape Boko Haram tell the same story of being forced to “marry” Boko Haram fighters after their capture.

Why can’t Boko Haram members find wives without kidnapping them?

To better understand this, we need to examine the status of the young men who move into these border areas, earlier as slave raiders and more recently as bandits, gasoline smugglers and terrorists. Within today’s social systems in the Lake Chad Basin, young men without money or connections find little possibility of social mobility. It is almost impossible to find a legitimate, well-paying job, and so they are trapped on the margins of society, scrambling to exist from day to day. In ordinary circumstances, such young men will never be able to afford a wife’s dowry, enabling them to become a baaba saré — in Fulani, “head of a household.” Without a family, they will be trapped in perpetual adolescence, not accepted as grown men even in their 30s and 40s.

Frontiers, and the violent possibilities for wealth that they provide, offer a solution to that problem. The borderlands between Cameroon and Nigeria have long been places where the lucky and ruthless can become rich, and wealthy people even wealthier. No wonder Boko Haram recruits spend so much time talking about girls and marriage; it’s an effective way to recruit.

What might this mean for policymakers concerned about insurgencies?

Boko Haram acts within century-old systems of regional border violence. Securing the borders might help combat the insurgency in the short term. Over the longer term, states in the Lake Chad Basin that want to prevent other insurgencies may wish to improve young people’s — and especially poor young men’s — social and economic options.

Regional governments haven’t shown much interest in such issues; because of the insurgency, they must respond to immediate challenges of social disruption, violence and famine.

Archaeologists working in Mali tell me that local Dogon residents similarly refer to the Islamist insurgents of Ansar Dine as slave raiders. Groups such as Boko Haram and Ansar Dine may be 21st-century terrorist movements, but they arise within historical systems that influence their strategies and actions. Understanding that context may help in creating effective policies to combat them.

Scott MacEachern is a professor of anthropology at Bowdoin College and author of the newly published “Searching for Boko Haram: A History of Violence in Central Africa” (Oxford University Press, 2018).