
For centuries the nomadic Tuareg tribe have crossed the Sahara desert, sometimes being led by the blind who used their heightened sense of smell and taste to pick a safe path across the ever-shifting sands.

Their men became known as the 'blue men of the Sahara' because the dye from their distinctive indigo scarves rub off onto their faces giving them a mysterious air. The Tuareg evoke images of a long forgotten and romantic age.

But behind the ancient way of life is a culture so progressive it would even make some people in liberal western cultures blush. Women are allowed to have multiple sexual partners outside of marriage, keep all their property on divorce and are so revered by their sons-in-law that the young men wouldn't dare eat in the same room.

Scroll down for video

Equality: The women of the Tuareg are respected members of society, who own the homes and the animals

Mothers: These two children were pictured in December 1967. Tuareg children traditionally stay with their mothers after a divorce

Religion: Much of the tribe, said to descend from one queen called Tin Hinan who lived in the fourth century, has now converted to Islam

History: The Tuareg have travelled across the Sahara for more than 1,000 years, the camels leading the way to fresh pastures

Mysterious: A Tuareg man in a traditional indigo veil, which is likely to leave his face with a blue mark across his skin

What is even more surprising is that even though the tribe has embraced Islam they have firmly held onto some of the customs that would not be acceptable to the wider Muslim world.

It is the men, and not the women, who cover their faces, for example.

Photographer Henrietta Butler, who has been fascinated by the Tuareg since she first followed them through the desert in 2001, once asked why this was. The explanation was simple.

'The women are beautiful. We would like to see their faces.'

But this is certainly not the only place the Tuareg, related to the Berbers of North Africa, differ from the Muslim world of the Middle East, and even other parts of their own continent.

Opinions: The Tuareg women, seen here arriving at the Tuareg Political Party speech in 2006, may not obviously be part of political life, but their opinion is highly valued by the men, who will likely discuss issues with their mother or wife

Owner: A nomadic Tuareg woman in front of her tent, with younger children sit inside. The mother's tent is the heart of the family

Freedoms: Before young Tuareg women marry, they are allowed to take as many different lovers as they want - as long as they abide by the strict rules of privacy which govern their society

Rules: This means the man must only arrive at her tent after dark, and leave before sunrise. Pictured: A Tuareg woman's decorated hands

Modern: It means Tuareg women marry later than other women in the area, although that still does not mean they have to give up their freedoms. They own the tents and the animals. Pictured: A family at a well south of Agadez

Concealed: The men begin to cover their faces at puberty, and will keep them covered in front of their elders and most women. The exception is their wives or girlfriends

Before a woman marries, she is free to take as many lovers as she wants.

'They turn a blind eye,' explained Butler. 'The young girls have the same great freedoms as the boys.'

THE BLUE MEN OF THE SAHARA: WHY DO THE MEN WEAR THE VEILS? The indigo veils the Tuareg men wrap so carefully around the heads have caught the imaginations of storytellers, filmmakers and travellers ever since they first came into contact with Westerners in the early 1800s. But why they wear the veils - which can cost hundreds, and are a source of great pride - is not known. Some say it is a practical decision, to keep the dust away. Others suggest it is to protect from the bad spirits - although whether it is bad spirits escaping the mouths of the person, or those escaping the mouths of others, is unclear. It is one of the many mysteries of the Tuareg, says Butler of the tribe she has been captivated by ever since her first trip. Advertisement

For years, the men of the Tuareg have been able to ride to a young woman's tent, and sneak into the side entrance - while his well-trained camel stands quietly and waits.

There, they will spend the night together - while the family, who all live in the tent, politely pretend not to notice.

Should the woman choose to welcome a different man into her tent the next day, so be it.

However, there is also a code of practice which none would dare break. Privacy is all important for this centuries old tribe of nomads, who once crossed the desert bringing dates, salt and saffron south, and slaves and gold north.

The idea of breaking the rules of courtship would be mortifying; as a result, the man is always gone before sunrise.

'The Tuareg are utterly discreet. Everything is done with utmost discretion and respect,' said Butler.

The relaxed customs around sexual partners has resulted in the girls getting married later than they may otherwise do, with the age of 20 not being uncommon.

Although, before then, they will have been wooed with poetry written by the men, who spend hours carefully crafting the words which they hope will win their beloved over.

But it is not a one-way street: the women are just as capable of putting pen to paper, using their own alphabet, taught to them by their mothers.

'The women also make poetry eulogising the men,' says Butler. 'There is high romance and idolatry.'

Unlike in so many other cultures, women lose none of their power once they marry either.

Bond: Every night, the families come together at the tents. The men are traditionally part of the women's group - not the other way round

Centre: It means the mother's tent is the heart of the community - although they do not eat together, and do much separately

Beautiful: It is the men who cover up their faces, while the women are happy to show off their faces - although they often cover their hair

Boundaries: The Tuareg travel across countries, but it has become harder since the colonialists carved Africa up. As a result, the Tuareg have been arguing for secession in Niger and Mali, which has often descended into violent conflict

Class system: Tuareg women pictured in Niger. The Tuareg are divided into castes, with the nobles at the top and peasants at the bottom

Lyrical: A Tuareg woman at a music festival in 2003. Young couples write beautiful poetry to each other

Lifeline: The camels are of vital importance in the Sahara, and are often the only thing a man is left with when he gets divorced

Ownership: Women keep the tent and all the possessions when they split, including the domestic animals which the tribe relies on to survive

Any visitor who goes to a camp would be vastly underestimating the power of the women in the tent if they believe their sole duty is to make the food and look after children.

In fact, she owns the home and the animals. And the animals are an invaluable resource to the Tuareg in the middle of the Sahara.

Journalist Peter Gwin recalled an elderly nomad once telling him: 'Animals are everything to a Tuareg. We drink their milk, we eat their meat, we use their skin, we trade them. When the animals die, the Tuareg dies.'

Many marriages end in divorce among the Tuareg. And when it happens, it is the wife who keeps both the animals and the tent. And it is she who normally decides that she’s had enough.

THE LEGENDARY QUEEN AT THE TOP OF THE TUAREG FAMILY TREE The Tuareg's many small groups are joined together by the same family tree - and at the top of that tree is the person who bought them all together. And it should probably come as no surprise for a tribe which views women in such regard, that person was a queen. Tin Hinan is said to have travelled south from modern day Morocco to what would one day become Algeria in the fourth century, where she became the first queen of the Tuaregs. It is from Tin Hinan - whose name translates as 'she of the tents' - that every noble family is said to descend. Takamet, her handmaiden who travelled by her side, is believed to be the ancestor of the peasant caste. Advertisement

It is unlikely there will be any quibbling over who gets what. Pre-nuptial agreements are the norm.

In practice, this often means a man is forced to return home to his mother, possibly with just his camel and nothing else.

His wife, meanwhile, will keep possession of everything she brought to the marriage and that includes the children.

The mother's camp, Butler explains, is the root of the community, the home everyone returns to - and this arrangement ensures it stays that way.

And there is no shame in divorce. Families will often throw their daughters a divorce party, to let other men know they are available once more.

But this is not a matriarchal society, where the women are in charge.

Butler explains it is still the men 'who sit and talk politics'. But even here, the women can be deferred to. They are often consulted for their views by their sons or husbands, and are quietly pulling the strings behind the scenes.

However, Tuareg society is matri-lineal, which means the families trace their lines through the women, rather than the men, right the way back to their first queen.

So, Butler explained: 'Traditionally, the man would belong to the woman's group, rather than the other way around.'

The preference for the women's line goes as far as man leaving his possessions to his sister's son as it 'is considered a stronger link to your family than to your own son'.

In other words, it can be guaranteed that your sister's child belongs to your sister, rather than a man's son, who cannot be absolutely guaranteed to share his genes.

But there is one tradition which is certainly far more unusual: it is highly rude for a man to eat in front of a woman who he cannot have sexual relations with, or any of his elders.

In front of his mother-in-law it is especially shameful.

'I didn't realise this until the I was having dinner with a Tuareg woman, who had brought her son-in-law as her travelling companion,' Butler recalled.

'We were all sitting down to dinner, and the man has his back turned. She said the poor man was completely horrified because he has to eat with his mother-in-law.'

But it is unlikely he would have ever complained about it, or felt sorry from himself. The very idea is horrendous to the Tuareg.

'You would shame yourself. The Tuareg will go to great lengths to maintain personal dignity. They will suffer,' said Butler.

'If they are not offered water, they won't ask for it - even if they are thirsty.'

Perhaps for this reason, the Tuareg welcome is legendary. They never forget to offer water, and travellers who appear on the horizon will always be 'treated like a king'.

Humiliation: For a Tuareg man, it is highly shameful to eat in front of his mother-in-law, who commands great respect

Huge family: There are thought to be more than a million Tuareg people, separated into different family groups

Yet could all of this be under threat? In recent years, the Tuareg - who have been arguing, and fighting, for independence for decades - have aligned themselves with extremist Islamist groups, as they try to further their cause.

Those partnerships have since crumbled, but now the Tuareg living in south-western Libya face a new threat - that of ISIS - while those living in Mali, Niger and northern Nigeria now have to contend with the rise of Boko Haram.

And then there is the general, cultural shift: Butler has noticed more of the women taking up the hijab.

And while she has been assured the women are wearing it for a fashion statement, rather than for religious reasons, she cannot be sure.

'It makes me very sad - you can see the regression,' Butler said.

Her fears are not alone. Andy Morgan, who managed Tuareg rockers Tinariwen, noted in 2013 some Tuareg considered the 'culture to be backward and irrelevant in the modern world, a folksy throw-back kept alive by meddling Western anthropologists'.

He continued: 'They would prefer their people to adopt Arabic, the language of the Quran and of the wider Muslim community... They deem certain other aspects of Tuareg culture, especially music and dance, to be licentious and ungodly and they object to the relative freedom and social power that Tuareg women enjoy.'

But there is hope this proud tribe, which has survived for more than 1,000 years, will hold fast to the traditions which make them so very different from all others.

After all, they believe their culture is preferable to anything they have yet to come across.

'They think they are superior to other races,' Butler said. 'They are very proud. They certainly consider themselves superior to us.

'Perhaps they consider other cultures a bit stupid and, dare I say it, primitive.'