Descendants of slaves on a voodoo pilgrimage in Benin

Every January, thousands of voodoo worshippers joined by crowds of tourists and descendants of slaves trudge down the long sand track leading to the beach at Ouidah in Benin.

The cars, motorbikes and women in wrap skirts with tribal scars on their cheeks head to the Gate of No Return monument overlooking the crashing waves of the Atlantic Ocean beach.

Erected in 1992 in memory of those packed on ships bound for the New World, it is a living reminder that the small Beninese coastal town of Ouidah once was the muster point for the black slave trade on the southern coast of West Africa.

Over the centuries, five million, possibly 10 million slaves took this route. No-one knows the exact numbers.

Though Ouidah is not the source of voodoo -- which originated in the old kingdom of Dahomey, modern-day Togo and Benin -- it was from here that the cult of the invisible and of natural spirits was exported to Louisiana, Brazil and Haiti.

After the fall of the communist regime in Benin, President Nicephore Soglo launched the first voodoo festival in 1993, making Ouidah voodoo's most famous place of pilgrimage for its 50 million followers worldwide.

- 'Way of life' -

"Ouidah is a duty of memory," said voodoo priest Erol Josue, who heads the national ethnology bureau in Haiti and who travelled to Benin with seven others to "make peace with the past".

"It's important to return to the ancestral land to accept oneself as a Caribbean," he added, his eyes thick with khol cosmetics and a heavy ring from Mali's Dogon tribe on his finger.

"To understand the behaviour of the Haitian people, you have to go back to the source."

Josue breaks off to film a video on his smartphone as a man climbs a bamboo pole nearly 15 metres (50 feet) high with his bare hands. The crowd goes wild.

Nearby, a group of men daubed with soil from head to toe dance in a trance to the rhythm of the djembe hand drum and make offerings to talismans.

"Voodoo is a way of life," said Gizirbtah, a young black American who changes her name whenever she travels to the home of her ancestors.

Gizirbtah, who works for a US airline, has been travelling across West Africa for two months with a dozen or so voodoo devotees from as far away as London and Chicago.

"Every day I do ablutions, purifications, prayers. But in the US voodoo is frowned upon, people don't understand," she said.

She turned to voodoo six years ago when she began what she said was an "internal quest".

"All my life, the story of my ancestors has echoed inside me," she said.

- 'Spiritual sadness' -

Strictly speaking, voodoo is not a cult of ancestors.

It is "the palpable representation of what we cannot see", said Vincent Harisdo, a choreographer of French, Beninese and Togolese heritage who is working on a dance project on voodoo.

"Every human has his inner 'fa' (a voodoo divinity), his other self. And we are all looking for our other self. Call that voodoo here or psychology in Europe," he added.

Gail Hardison, a 57-year-old American, chose science over spirituality to get to know her origins.

Several years ago she had a DNA test that revealed her ancestors came from northern Cameroon.

This year she has brought her ancestral quest to Benin.

"I'm not a follower but I respect voodoo as a religion. Voodoo isn't about dolls with pins in it," she said.

The dancing and the tourists gives a folklore feel to the festival, a weeklong event marked by the beach procession on January 10 every year.

But despite the crowds, the noise and the scorching sun, Hardison said she feels a "spiritual sadness" in Ouidah.

Looking at the Gate of No Return, where hundreds of visitors are crowded together trying to find some shade, she says: "I wish it could have been different for all the people who passed through here."

"I feel them with me."