Travel: Warriors of the sky gods and Nyale from the sea: Indonesia does not stop at Bali. Beyond lies an extraordinary archipelago, islands of strange rites and unshakeable friendliness. We visit Sumba and Flores

AT MIDNIGHT the howls on the hilltop begin: loud, urgent cries in the darkness. Once, twice, the call is given, then from the sea comes a faint 'Hoo-hoo-hoo-hoooo . . .' The old priests on the hilltop shake their feathered headdresses and nod: Nyale, goddess of the sea, is coming to shore. The Pasola can begin.

There is no other festival in Indonesia quite so bizarre as the Pasola; no island quite so curious as Sumba where it takes place. Far south of the islands that trickle east of Bali, Sumba lies remote and undeveloped, caught in an an extraordinary archipelago, an eddy of unique animist culture.

When it was called Sandalwood Island, Sumba attracted a host of Chinese, Japanese, Arab and Malay traders. But once the sandalwood was gone, Sumba sank into obscurity, too far, too poor and probably just too weird to interest the former Dutch rulers. It was 1912 before a colonial administration was installed, and that was indirectly, with local rajas still wielding most of the power. When Indonesia gained independence, it took six months for the news to reach east Sumba.

Even the missionaries failed to make inroads. Neither Islam nor Christianity has eroded Sumba's ancient Merapu religion. Buffalo, pig and dog are still sacrificed at funerals and chicken entrails read by shamans. The dead are wrapped in lengths of priceless tie-dyed ikat cloth and buried in massive stone tombs. Isolation has fallen on the island like a shroud.

You could hardly call it a busy place, but the Pasola still lures thousands of foreigners. It is held in four locations in the west of the island a few days after the full moons of February and March, and is an extraordinary enactment of a unique religion. Among Indonesia's many animist festivals, the Pasola - literally, 'throw spear' - ranks a cut and thrust above the rest, its danger as intense as its drama.

The festival centres on a violent jousting match between villages representing the rival forces of the Lower and Upper Worlds. Symbolically, this is a battle to keep the balance between the Merapu, gods of the sky, and Nyale, goddess of the sea. In practice the purpose is to draw blood, considered the greatest gift that can be given to the gods, and even spectators have no immunity. You attend the Pasola at your peril.

On Bali's tame and cosy shores, it sounded irresistible. I headed east and felt Pasola passion mounting as I crossed from shore to shore. 'You're going to Pasola?' asked villagers. 'Awas] Take care]' And they rolled their eyes to heaven and murmured prayers.

But the closer I got, the more elusive the Pasola seemed: no one could tell me exactly when it would begin. The high priests, or ratos, alone know the annual festival date, and even they are dependent on the arrival of a multi-coloured seaworm on the beaches. These squiggly little worms (representing the body of the goddess, and also named nyale) appear only in the first few months of the year, just before the planting season. From their condition, the ratos can tell if the harvest will be successful: rotten worms indicate a rain-damaged crop; biting, pitted worms a plague of mice. Only the colours are always good: blue worms are said to come from the goddess's hair, yellow ones from her betel-stained lips, and red from her blood.

It was strangely quiet when I finally arrived at Wanokaka, the small coastal village where the Pasola was to take place. But as dusk fell there was mounting excitement. From every thatched house came a chatter of voices. Young men appeared on the road, leading horses adorned with bright ribbons. At midnight, they told me, the ratos would call from the hilltop. Only then should I go to the beach and wait for the worms.

But I was in no mood to be patient. I found a guide to take me to the priests' sacred hilltop abode, and just before midnight we ventured out, stumbling over the tombs of ancestors in an ancient burial ground. Suddenly, I heard a sound that stopped me in my tracks. Like the howl of wolves, it pierced the silence.

'The ratos,' whispered my guide. 'They are calling to the goddess.' And he pointed to a rock where five dark figures in feathered headdress stood, daggers at their waists.

I was not welcome. The ratos were angry. I slunk under the eaves of the house as they called once again and waited for the answering cry from more ratos on the beach. When they made their way down the hill, I warily followed. Murmurs came from the houses as we passed. No one was asleep. It was three hours to sunrise and unusually cold.

Gathered on the beach was an extraordinary collection of ratos, wizened old men in red and black turbans and ikat sarongs. They stood apart while villagers crouched on the rocks, watching the sea for a ripple of life. But nothing. Only silence and cold.

Gradually, more people arrived and dozens of men on horseback bearing long wooden spears. The sky grew pale, the sea turned a shimmering pink. Suddenly, two ratos approached the water. The crowd surged forwards. 'Nyale? Have the nyale come?' Slowly the ratos walked into the sea, and scooped up water. It rippled with colour: the body of the goddess, her hair, her lips, her blood. 'Nyale]' cried the crowd. 'Will the harvest be good?' Then, before the old men had pronounced that the worms were fat so the harvest would be fine, the villagers splashed after them, laughing and chattering, scooping up worms into baskets and bowls.

'Eat them, they're nice]' cried a jovial old woman, and handed me a squirming handful. 'Raw is good, but fried is best.'

The ratos took no part in these larks. They had rituals to perform. They began their own symbolic battle, hurling taunts and curses at each other with astonishing ferocity. The oldest crouched on a rock. A dozen chickens were placed before him and one by one he slit their throats and bellies and prodded their entrails. 'Will the harvest be good?' asked the onlookers. 'Yes,' the wise men murmured with no flicker of emotion, 'the harvest will be fine.'

At the far end of the beach, hundreds of horsemen had gathered, bristling with blunted wooden javelins. Battle was about to commence. The fighters confronted each other, their horses ablaze with red ribbons. Suddenly they charged, and the air was thick with flying spears.

Excitement broke like a wave upon the crowd. The strong little Sumba horses, ridden bareback, pounded across the sand. In groups of 10 or 20, the men kept charging. The speed and fury were incredible. Within minutes a rider was hit and dragged from the battleground. The crowd cheered. 'Is he dead? Only injured] Blood has been spilt] The gods will be pleased]'

After several more sallies, the battle moved inland for the major conflict on a grassy field, watched by local officials and tourists with island police on hand in front of the crowd.

The battleground erupted with flying spears and charging horses, fiercer than anything we had seen on the beach. 'Awas] Take care]' gasped my neighbour as the horsemen galloped close by. Almost at once, a volley of spears flew towards us. The crowd ducked and yelled, and two men were hit. 'Injured]' The assailant triumphantly punched the air, his women supporters screaming a battle cry just as their ancestors did when their men went hunting for heads.

As the sun rose, the fever of battle increased. The police became edgy, the atmosphere tense. After every short lull, the action resumed more violent than before. A scuffle broke out: riders had abandoned their horses and were throwing rocks. The sound of gunfire sent the crowd scurrying in panic into the hills. The police fired into the air again and the fighting ceased. My neighbour laughed. 'It often ends like this,' he said as the crowd drifted home. 'Such is the excitement; such is the Pasola.'

Flights: Hermis Travel (071-731 3819) offers return fares, London to Bali via Jakarta, with Garuda Indonesian Airlines, from pounds 525. Sister airline Merpati offers flights daily from Bali to Flores, thrice weekly to Sumba, pounds 97 and pounds 85 one way, if bought in the UK through Garuda (071-486 3011). Save at least 25 per cent by buying tickets in Indonesia in local currency.

Books: Two useful guides are Indonesia: A Travel Survival Kit, and South-east Asia on a Shoestring (Lonely Planet, pounds 14.95 and pounds 12.95).

FIRM FRIENDS AFTER THE QUAKE

AN OLD man came out of his bamboo hut. With a little bunch of twigs he swept the leaves from his daughter's tomb and motioned that we should make ourselves comfortable on the cool stone slab. Such acts of kindness were common in Nuamari, a small hamlet in the mountains of Flores, where we had fled after one of the most violent earthquakes in decades to hit Indonesia.

Yards from the tomb a fresh grave had been dug for Nuamari's own victim of the disaster, a four-year-old girl. There the dead stay close to the living. Loved ones are buried beside the family home. Thus we found ourselves lying on Fasia Bala's tomb in the shade of a tree.

'You must eat,' said the village chief, offering ubi roots, steaming chunks of white vegetable tasting like bland potato. Ten of us, Western tourists, had slept on open ground in the village, huddling with people who had lost their homes. Sporadic tremors made it dangerous to enter the few buildings that had survived, and we had lain awake, wondering if there was worse to come.

The previous day we had stumbled around as great shuddering vibrations rocked the earth beneath our feet. The air had thundered with the sound of collapsing buildings, and people had run wailing from their homes clutching crucifixes. Dogs were barking and a tethered monkey screamed in terror. We had felt certain we would die.

Then the earth had settled and the air had been heavy with dust. A silence had descended, broken only by sobbing. We had fled to higher ground, fearing that lakes in an extinct volcano above us would burst from the crater, flooding the valley.

'The three remaining members of the Beatles are to get back together. Paul, Ringo and George have agreed to take part in a documentary series about the Fab Four . . .' This was not what we had tuned into the BBC World Service to hear, but it had been a link with home as we struggled through lush undergrowth, an hour after the earthquake, on our way up to Nuamari.

The people of Nuamari had made us welcome, though around us lay the rubble of their homes. Walls had fallen away to expose shattered beds, tables and chairs. The villagers' few possessions lay buried in the debris. It would be a few days before news reached us here that 2,200 people had lost their lives in the disaster, a week before a helicopter arrived to take us away.

Every day we went to wash in the stream, wobbling on slippery rocks, as hordes of onlookers stared at our white bodies. Eyes followed us everywhere - at dawn when we awoke, and in the evening as we sat beside the fire. We grew used to an audience. The children were fascinated by everything about us. To them our rucksacks contained magical toys. A calculator provoked squeals of delight and faces broke into grins as a personal stereo whispered music into each child's ears. We showed them card tricks, made paper aeroplanes, drew pictures. Their easy laughter brought us comfort.

'You like him tonight? Satay?' asked Francis as we sat outside a hut, making a fuss of a young black dog. We protested in horror - earlier we had seen a dog slaughtered and skinned - but Francis was joking. He had been a guide for tourists who came to explore the volcanic landscape, but we were the last he expected to see for a long time.

Ketut had been sent from his beloved Bali to take up the post of village policeman. He was 21 but told us he was 22. A more senior officer had been taken to hospital with malaria, so responsibility for the village - and its unexpected guests - fell to Ketut alone. That morning he had set off on his motorbike to look for people killed or injured in a landslide. He had returned horrified. 'It is bad,' he said, shaking his head. 'I tried to pull bodies out but they are buried too deep.' He could not sleep so we told him to think about his family back home in Bali.

One day an injured Dutch tourist walked into the village with a deep cut on the crown of his head. He and his wife had scrambled through the window of a guesthouse during the earthquake, and a chunk of masonry had struck him. The injured man had a fever and needed urgent medical attention, but there was no hospital for miles.

Ketut decided to take him on the back of his bike to a medical centre a few miles away. This meant negotiating a road made treacherous by falling rocks. It was suggested the man's wife follow on a mule led by one of the locals, but she could not ride and went on foot. It was dark when Ketut returned to say the couple had reached the centre and were safe.

It was the wet season in Flores, but miraculously there had been only a brief shower since the earthquake. We knew our luck could not hold out much longer - if a helicopter was to land in the mountains, it would need clear weather, and the chance of an air rescue seemed ever more unlikely. 'Maybe you walk?' suggested Ketut, frowning, knowing this would mean a 56km trek to the port of Ende, along a twisting mountain road. 'Will your country send a helicopter?' He sounded doubtful. We, too, were beginning to wonder.

Our doubts increased until, on the seventh day, we decided to walk. The villagers were worried. Despite their suffering, they had still shown concern for our welfare. But as we ate our breakfast with them on that last morning we heard the helicopter. The locals ran cheering into the road. 'Tourists] Tourists] Heli] Heli]' they yelled, grabbing at our sleeves, laughing, exulting.

It was raining when we returned to Britain, the trees were bare and the sky grey. There was a letter waiting for us from a young boy we had befriended in the village, 'When you and your friends take off, many people cry because they love,' it said.

(Photograph omitted)