World leaders met here Thursday on the Asian earthquake and tsunami disaster which hit 11 mostly Asian countries, killing more than 146,000 and causing unprecedented devastation.

With up to four billion dollars already promised in aid, the major international summit will discuss strategies for overcoming the catastrophe, including reaching those urgently in need as well as rebuilding the areas worst hit.
Here is a factfile of the five regions worst affected by the catastrophe.

Aceh, Indonesia
This province on the northern tip of Sumatra has already been torn apart by civil conflict over the past 28 years.

An estimated 12,000 people, many of them civilians, have been killed and thousands more displaced since the Free Aceh Movement began its fight for independence in 1976. Martial law was lifted last year, but Indonesian troops remain a heavy presence and gunbattles are common.

Aceh has a centuries-old history as a busy trade port and kingdom. It became part of Indonesia when it was forcibly annexed by Jakarta after Dutch colonialists withdrew from the archipelago in 1949.

The province's 4.5 million population, spread across 55,000 square kilometres (21,500 square miles) of coastal flatlands and more mountainous interior, is almost entirely Muslim, devout but not considered fundamentalist. Despite being rich in natural resources such as oil and gas, the area remains deeply impoverished. Many industries employ migrant Javanese workers and critics accuse Jakarta of plundering the region's fuel wealth.

In November Indonesia's new President Susilo Bambang Yudhoyono visited war-torn Aceh to pledge peace, urging rebels to accept special autonomy granted them by Jakarta, a call for unity that he reiterated in the wake of the disaster.

Andaman and Nicobar Islands
The archipelago of 572 islands, only 36 of them inhabited, stretches over 800 kilometres (500 miles) and is home to some of the world's oldest and most remote communities.

There are six tribes including the hunter-gatherer Jarawas and the Stone Age Shompen aborigines who have lived for up to 60,000 years without being touched by modernity.

Despite a ban on visitors to many tribal areas, numbers were already dwindling before the tsunami struck. The islands also boast an immense wealth of biological diversity.

Andamanese are not divided by sectarian boundaries and inter-community marriages are common. Hindu, Muslim or Christian festivals all take place on the islands. The Nicobarese, who account for a quarter of the archipelago's population of 356,000, are the most integrated of the tribes, carrying significant political power.

The islands, a union territory, have one seat in parliament and apart from the 1999 elections have always voted Congress Party.

The islands, some 1,200 kilometrs southeast of the Indian mainland in the Bay of Bengal, are surrounded by coral reefs, sandy beaches and clear water reputed to be among the most beautiful in the world, making them popular with Western tourists, a key industry.

The islands were used as a penal colony by British colonialists in the 19th century, imprisoning Indian freedom fighters in the infamous 'cellular jail' in the capital Port Blair.

Today the Andamans are home to several secretive Indian military bases.

Eastern Sri Lanka
Three decades of ethnic bloodshed in Sri Lanka has claimed over 60,000 lives, many of them on the east coast which took the full force of the tsunami that overwhelmed around three-quarters of Sri Lanka's 1,340-kilometre coastline.

The conflict between Tamil Tiger rebels, who control areas in the north and east of the island and are seeking self-rule, and the mainly Sinhalese government in Colombo has also forced over a million people to flee the war-torn country. About 90,000 of them still live in refugee camps in neighbouring India.

The Tamil minority makes up about almost one-fifth of the country's near 20 million population and is based mostly in the north and east.

Tamils are predominantly Hindus, who make up 15 percent of the population
by religion, with Buddhism the most practised at 70 percent. Christians and
Muslims each make up about 7.5 percent.

Sri Lanka has diversified from its mostly agriculture-based economy but was on track for a record trade deficit in 2004 amid rising global oil prices. The country imports all its fuel. Tourism has been growing steadily for the past decade, representing both directly and indirectly about two percent of Sri Lanka's gross national product.

A ceasefire between the government and Tiger rebels has been in place for almost two years as part of a Norway-brokered peace attempt.

However, four previous peace bids since 1985 have ended in failure and a war of words in December suggested neither side was ready to return to the bargaining table.

But in the wake of the disaster, which has inflicted heavy tolls and used up resources on both sides, observers have said the disaster has lessened the capability of both sides to renew armed conflict.

Southern Thailand
The peninsular south of Thailand and its outlying islands are hugely popular with Asian and Western tourists for its unspoiled beaches, tropical climate and coral reefs. Tourism has been one of the area's fastest-growing sectors.

The tsunami hit six provinces on the Andaman Sea, Phang Nga, which was
worst-hit, Phuket, Ranong, Krabi, Trang and Satun. Almost two million people live in the provinces which cover almost 8,000 square miles.

Phuket island led the way in tourism and is now one of Asia's most popular resorts for wealthy expats, many of whom have built luxurious homes on the island.

The province draws 2.75 million tourists and two billion dollars, more than a quarter of the income of the tourism industry which nationally accounts for six percent of Thailand's gross domestic product.

Krabi and Phang Nga were also beginning to cash in on the tourist dollar as major hotel chains moved in. Many have now been devastated.

Mostly Buddhist Thailand faces a Muslim insurgency in the south but the three provinces affected, Yala, Narathiwat and Pattani, are further south of the tsunami-hit area, near the border with Malaysia.

Tamil Nadu, southern India
Tamil Nadu was the worst hit of three southern states badly affected when some 2,260 kilometres of the Indian mainland's southern coastline was battered by the tsunami.

With a population of some 62 million spread over an area of 130,000 square
kilometres, Tamil Nadu is best known for its Hindu temples, textile industry,
particularly silk, and beaches, which were seeing an upsurge in tourism.

Recent private and public investment has been made in infrastructure, nuclear power and hotels.

Tamil Nadu has an unbroken coastline on the Bay of Bengal, with the interior composed of rocky highlands, farmland and dense forests rich in wildlife.

Its low-lying plain, bounded by the Eastern Ghats in the north and Nilgiri and Anai Malai Hills to the west, is mostly agricultural dotted with industrial centres.

The state has its own bicameral legislature besides representation in India's federal legislature.

Home to ancient civilisations up to 300,000 years old, the area is believed to have welcomed the first Dravidians around 1500 BC. Its capital Madras, now officially called Chennai, is India's fourth-largest city.

Located on the spice route, the port city has been a popular trading centre for more than 2,000 years. Madras is now a bustling commercial and manufacturing centre with a population of 4.2 million.

Neighbouring coastal states Kerala, to the east, and Andhra Pradesh, to the north, which were also hit badly by the tsunami, have populations of 32 million
and 76 million respectively.

The former French enclave of Pondicherry, today a union territory with a population of 975,00, also suffered heavy casualties.