Yasmin Alibhai-Brown: Zanzibar and the darkness in paradise

Going back was a life lesson in the potency of the whole historical truth

I went to Zanzibar in June to make two radio documentaries. Oh lucky me, you might think, how wonderful. Increasingly popular with holidaymakers, it offers emerald forests and azure seas, blue skies with playful clouds, palm trees, coffee scented with cardamom, golden beaches, delectable food. They know not the bloodshed and agony that shaped this place. Nothing is as it has been made to seem. There is no innocence here, no easy forgetfulness – not for the inhabitants. They smile and laugh with visitors and try to please them (and because they are naturally hospitable, it has authenticity) but all the while unsettled scores and untold stories pulsate and throb through the veins of this part of the Tanzanian nation.

History has been buried here, deep in the sands, but never washed away. I often went to Zanzibar as a child, with my mum, who was born in Dar es Salaam. We would take a crowded ferry and stay at a hostel for poor women and their kids who wanted a subsidised break by the sea. The women in the local mosque provided lunch and we had a wonderful time. The island, a fabulous mix of Arab, African, Indian and Persian cultures and peoples, was utterly unlike my racially divided hometown, Kampala, Uganda. Then one day my mum told me about the thousands of black slaves who had been captured in the hinterlands and brought to the island to be sold. She took me to Bagamoyo, the slave port on the mainland: the word means "lay down your heart". That trade went on from the seventh century to, it is claimed, the beginning of the 20th century.

Through early history, enslavement was common around the world and East Africa was just one more lucrative location. But here the abomination went on longer than at any other time or place. The traders were mostly Arab, though some Indian merchants were actively involved. Those who captured and sold the humans to the businessmen were local African chiefs and henchmen.

A febrile young child, I was distraught when I learned that Muslims had perpetuated this evil. How could it be? The Prophet Mohammed had freed Bilal, a black slave, and asked him to make the first-ever call to prayer. Surely that meant something? And as the years went on and we learned to look back with abhorrence at the practice of owning and exploiting humans, how come there was no acknowledgement of this systemic injustice in Zanzibar?

The questions circled around in my head obsessively when I was a young teen. Then came 1964, and the island detonated. A revolution led by African soldiers deposed the constitutional monarch, Sultan Seyyid Bin Abdullah. It was, in part, retaliation for slavery by people and upon people who were not responsible. It felt as if some ancient God of vengeance had risen from the sea. They slaughtered anyone who looked Arab and some Indians too, took their daughters to rape and use, confiscated their properties and banished many. To this day there is no list of the dead – those tortured and dumped into the sea – the disappeared and the exiles. A few years on, the coup leaders went for Zanzibari Persians, plucked several beautiful young girls of the most affluent families – some as young as 14 – and forced them into marriage with brutish military men.

Mum and I never went back to our favourite place. Terror spread among Asians in all East African countries. In 1972 Idi Amin threw us out of Uganda, but we were not subjected to the bloody ethnic massacres of Zanzibaris. Tanzanians celebrate the revolution every year and the important transformations it brought in education and health, but there is no mention of the murders and rapes.

For years I have wanted to reveal these veiled stories. And I was finally given that opportunity by the Heart and Soul strand on BBC World Service. Even before we left, there was nervousness among academics, writers, fixers and exiles. I could understand the anxiety. Politicians use bad history for worse politics and they had done so for decades in Zanzibar.

I'm glad we had the courage to overcome the reservations. I interviewed Leila, 99, whose grandparents were enslaved. She spoke of babies, her father's siblings, who were thrown into the forests. When we turned the tape off, her eyes glazed over and she threw up blood all over her lovely satin dress and me. There is a memorial to the slaves now, near the church built by Christians who raise praise for the anti-slavery campaigner David Livingstone. We saw holding caves near a beach where, it is alleged, human cargo was smuggled until the 1920s. I discovered that people in my own Shia community made huge profits selling and buying people, and also that the richest, Sir Tharia Topan, became a passionate abolitionist. Europeans were also involved and Africans were suppliers. Yet they blame only Arabs – a travesty. There were fascinating differences between Atlantic and East African slavery. The latter allowed the children of master and slave to become part of the family and to rise to power. But the bitterness is the same.

The revolution was, some said, payback. But when we met the victims, some of whom had lost so many relatives, that justification felt like an excuse. Those who knew the violated and stolen girls cried as they spoke. They were taking risks talking to us, but "it was time", they said. I spoke to many in Swahili. One witnessed the gutters running with Arab and Indian blood, "like that of chickens slaughtered for Eid festivities".

Going back was a life lesson in the potency of the whole historical truth. Those of Arab descent feel too defensive about the slave trade and focus on the revolution; Africans dwell on the trade and expect no mention of the barbaric acts of the revolutionaries.

Zanzibar is picking up – our leader, the Ismaili Aga Khan, has just spent millions restoring the old Arab garden and main square. Zanzibaris are taking pride in their island once more. But I am apprehensive that it could all go wrong again because too much is unresolved. There will not be real, deep healing between the citizens of various ethnicities until everyone talks more honestly about past injustices. Without that, paradise is but an illusion.

Return to Zanzibar is broadcast on the BBC World Service, 25 and 26 of July