He had found Serengeti. In the years since White's excursion under "the high noble arc of the cloudless African sky," Serengeti has come to symbolize paradise to many of us. The Maasai, who had grazed their cattle on the vast grassy plains for millennia had always thought so. To them it was Siringitu - "the place where the land moves on forever."

The Serengeti region encompasses the Serengeti National Park itself, the Ngorongoro Conservation Area, Maswa Game Reserve, the Loliondo, Grumeti and Ikorongo Controlled Areas and the Maasai Mara National Reserve in Kenya. Over 90,000 tourists visit the Park each year.

Two World Heritage Sites and two Biosphere Reserves have been established within the 30,000 km² region. It's unique ecosystem has inspired writers from Ernest Hemingway to Peter Mattheissen, filmakers like Hugo von Lawick and Alan Root as well as numerous photographers and scientists.

The Serengeti ecosystem is one of the oldest on earth. The essential features of climate, vegetation and fauna have barely changed in the past million years. Early man himself made an appearance in Olduvai Gorge about two million years ago. Some patterns of life, death, adaptation and migration are as old as the hills themselves. A unique combination of diverse habitats enables it to support more than 30 species of large herbivores and nearly 500 species of birds. Its landscape, originally formed by volcanic activity, has been sculptured by the concerted action of wind, rain and sun. It now varies from open grass plains in the south, savannah with scattered acacia trees in the centre, hilly, wooded grassland in the north, to extensive woodland and black clay plains to the west. Small rivers, lakes and swamps are scattered throughout. In the south-east rise the great volcanic massifs and craters of the Ngorongoro Highlands. Each area has its own particular atmosphere and wildlife.

In the open grass plains during the rainy months from November to May hundreds of thousands of wildebeest and Burchell's zebra congregate. The area is the starting point for one of the great wonders of the world: the Serengeti annual migration. Towards the end of May when the grass becomes dry and exhausted, the wildebeest start to mass in huge armies. All is far from peaceful, for it is the rutting season and each male tries to establish a stamping ground. Eventually, after several dummy runs, the animals begin their trek in a column several miles long to the permanent waters in the north of the Park. After moving westwards, the migration divides by some uncanny instinct, one group turning north-east and the other due north. Once started, little stops the stampede: hundreds often drown at a time in the broad Mara river in the north. Today, the Serengeti National Park, the Ngorongoro Conservation Area, and the Maasai Mara Game Reserve across the border in Kenya, protect the greatest and most varied collection of terrestrial wildlife on earth, and one of the last great migratory systems still intact.

Although outnumbered eight to one, the zebra join in the migration, maintaining their family units of about a dozen members, each with a dominant stallion. Their yelping bark combines with the bleating of the wildebeest to give the typical sound of the migration. Lion, cheetah, hyena and hunting dog follow the wildebeest and zebra, making sure that only the fittest survive. In November, when the grazing is finished in the North, this army of animals surges back to the now green pastures of the south, where they calve and mate before starting the entire cycle again. Normally, the best time to see the animals here is during January and February.

The Serengeti's climate is usually warm and dry. The main rainy season is from March to May, with short rains falling from October to November. The amount of rainfall increases from about 508mm on the plains in the lee of the Ngorongoro Highlands to about 1,200mm on the shores of Lake Victoria. All is lush and green after the rains, but a gradual drying up follows which restricts plant growth and encourages the animals to migrate in search of permanent waters. With altitudes ranging from 920 to 1,850 metres - higher than most of Europe - mean temperatures vary from 15 degrees to 25 degrees Celsius. It is coldest from June to October, particularly in the evenings.

The Serengeti is the jewel in the crown of Tanzania's protected areas, which altogether make up some 14% of the country's land area, a conservation record that few other countries can match.