According to the Christian tradition, shepherds were the first to visit the infant Christ.

These days, about 12,000 families still rely on herding in the West Bank.

The United Nations is warning that their livelihood is under threat, because of drought and Israeli restrictions on their movements.

A flock of sheep and some scrawny goats huddle in a rough stone enclosure on a barren hillside south of Hebron.

They belong to Mohammed Abu Ali and his wife Fatima, and their family.

They live in a cave next to the sheep pen.

Fatima says the animals are all they have.

"They give us a rough time but they are good when we are desperate for money," she said. "They have to be well looked after, they have to be vaccinated - but at the end of the day, they support our life."

Mohammed says his ancestors have herded here for centuries.

But now times are hard. There's been a drought for several years.

If it rains, the rocky hillsides will be green. But now it is dry and bare with very little for the animals to eat.

Mohammed and his family live in an area of the West Bank that is under total Israeli control.

He says it is almost impossible to get permission to build new wells.

"Everything is forbidden, especially anything involving concrete," he said.

"To build a new well is not allowed. There are wells here but they are small and the water is not enough."

In a statement to the BBC, the Israeli civil administration said it was not aware of requests to build wells in the area - but it was ready to consider people's problems.

At a village nearby, sheep jostle to reach metal feeding troughs full of grain, as there is not enough grass to sustain them.

Fodder can be expensive, but many herders say they have no other choice.

'Safety and security'

In the past shepherds would have wandered around to find greener pastures.

But now they say they face harassment from Jewish settlers when they move with their animals.

And their traditional grazing grounds are used by the Israeli army for military training.

The army says most of the land does not belong to the shepherds. In a statement, it said the restrictions on movement were for the safety and security of civilians.

The United Nations says a whole way of life is under threat.

Hamid Qawasmeh, from the UN Office for the Co-ordination of Humanitarian Affairs, said the future for these herding communities looked grim.

"People can't access the land, they can't herd as they did in the past," he said. "We have less and less rainwater every year, so with all these problems combined we are not seeing a very bright future for these populations."

Back at Mohammed Abu Ali's cave, tea was being prepared.

On a pile of blankets in the corner, his baby grandson, Jihad, lay cradled in his mother's arms.

It isn't clear if he will grow up to be a shepherd like his ancestors or if this ancient way of life is slowly coming to an end.