'The Woman King' tells the story of the Agojie. But in real life, the fierce women warriors played a controversial role in the translatlantic slave trade.

• The Agojie were fierce women warriors in the ancient Kingdom of Dahomey in West Africa.
• They were national heroes and symbols of female power, but also helped the rise of the 18th century slave trade.

"The Woman King," a new film that stars Viola Davis and is directed by Gina Prince-Bythewood, is a chronicle of Black female power. It tells the story of the Agojie, fierce women warriors in the African Kingdom of Dahomey in the 1800s, as they battle enemies that threaten their way of life.

But since its release last week, some fans have criticized the movie for minimizing the kingdom's role in the transatlantic slave trade, calling for a boycott over what they allege are historical inaccuracies.

The true history of the Agojie's role in Dahomey's involvement in slave trade is complex. While the "Dahomey Amazons" were symbols of strength and power — inspiring other films like "Black Panther" — they were also complicit in the capture, creation, and sale of other African people.

"On the one hand, these women were some of the strongest warriors best able to defend African society, and are seen as national heroes. Yet depending on where you are in society, you may have a different take on the role they played in history," Patrick Manning, professor of world history at the University of Pittsburgh, told Insider.

One of the largest exporters of enslaved Africans

Dahomey first rose to power as a centralized and militarized kingdom in West Africa in the 17th century. It wasn't until the 18th century, during the peak of the Atlantic slave trade, that the kingdom expanded its might.

In 1727, Dahomey conquered the coastal Kingdom of Hueda, taking control of the port city Ouidah. This would become its main base for trade with European powers, and marked the start of its active participation in slave trade.

Dahomey soon became a key player in the trafficking of Africans, which proved to be one of the most profitable exports at the time, according to Manning. Armed with muskets they obtained from foreign nations through their export of slaves and other goods, Dahomey's armies captured people from nearby kingdoms and villages to fuel their supply of slaves.

Dahomey's involvement in the slave trade was fueled by European demand for cheap labor. Africans were left with scant choices: Would they benefit from this opportunity to steal people and sell them, run away, or fight back against foreign powers?

"It certainly wasn't Africa that came up with the idea of the slave trade, but their involvement was a response to an existing, increasing demand," Manning said.

Historians estimate that nearly 1 million enslaved Africans were put on ships to the Americas in Ouidah between 1659 and 1863, making the port city the second largest supplier of African captives to the trade.

The Agojie aided Dahomey's military

Dahomey was ruled by King Ghezo, who came to power in 1818 after he staged a coup d'etat against his half-brother. Ghezo, who spied an opportunity to boost Dahomey's military and monetary power, forged a partnership with Francisco Félix de Sousa, a Brazilian merchant and slave trader who set up post in the port city of Ouidah, Manning said.

The Agojie warriors played a significant role in Ghezo's campaign for expansion through the export of Africans.

The all-women battalion was established earlier in the 17th century under King Houegbadja, the third king of Dahomey. (Some accounts attribute the founding of the Agojie to Houegbadja's daughter, Queen Hangbe, who is said to have enlisted female bodyguards to protect her.) The warriors were barred from having children or marital relationships, and subjected to intense, demanding training. They raided villages under the cover of darkness and swiftly executed prisoners.

The Agojie reached its peak and became increasingly militaristic in the 19th century under Ghezo, who formally incorporated them into Dahomey's army. The kingdom was embroiled in ongoing wars, which led to a decline in the population of men and an opportunity for women to fill in those gaps on the battlefield.

The Agojie were sent out on annual campaigns to conquer nearby kingdoms and capture slaves for trade, Manning said. They also helped to swiftly suppress conspiracies or rebellions among slaves before they could escalate into violent uprisings.

The African kingdoms had rules against enslaving people within their own domain, but went to war every year to enslave others, according to Manning.

"They didn't speak the same language and lived far from each other. They were seen as different, as enemies," Manning said.

The end of the Kingdom of Dahomey

From the 1830s onwards, Dahomey and other African kingdoms saw a decline in profitability in slave trade, according to Manning. Instead, they began to shift their focus to exporting palm oil, which was used to make soap in Europe.

"Ghezo was in a bit of a bind during the 1830s and 1840s: Even though prices for slaves were declining, you could still make good money out of selling slaves, which was still more profitable than selling palm oil," Manning said.

Yet even the production of palm oil required the use of captured Africans. It wasn't until 1852 that King Ghezo finally agreed to end Dahomey's participation in the slave trade, after years of pressure by the British government, which had abolished slavery in its colonies in 1833.

The Agojie remained a significant military force until 1892, when the French conquered the kingdom and disbanded the warriors. French colonizers barred women from political leadership, serving as warriors, and educational opportunities, Leonard Wantchekon, an economist at Princeton University and Benin native, told the Washington Post.

"The French made sure this history wasn't known," Wantchekon said. "They said we were backward, that they needed to 'civilize us,' but they destroyed opportunities for women that existed nowhere else in the world."