After Yazidi campaigner and former sex slave Nadia Murad won the 2018 Nobel Peace Prize Friday, here is some background about her community.

- Ancient faith -

Mainly living in remote corners of northern Iraq, the Yazidis are followers of an ancient religion with more than half a million Kurdish-speaking believers.

The faith emerged in Iran more than 4,000 years ago. It is rooted in Zoroastrianism but has over time integrated elements of Islam and Christianity.

With no holy book and organised in castes, Yazidis pray to God facing the sun and worship his seven angels -- first and foremost Melek Taus, or Peacock Angel.

- Long persecuted -

Yazidis discourage marriage outside of their community and even across their caste system.

Their unique beliefs and practices, such as a ban on eating lettuce and wearing the colour blue, have often been seen by other Iraqis as satanic.

Orthodox Muslims consider the Peacock a demon figure and refer to Yazidis as devil-worshippers.

Being non-Arab and non-Muslim has placed Yazidis among Iraq's most vulnerable minorities.

Persecution by Saddam Hussein forced thousands of families to flee the country. Germany is home to the largest community abroad.

The Iraqi Constitutions of 2005 recognised their right to practise their religion and gave them seats in the central and autonomous Kurdish parliaments.

- Islamic State victims -

On August 14, 2007, massive truck bombs almost entirely destroyed two small Yazidi villages in northern Iraq. More than 400 people died in the attack.

In August 2014 Yazidis struggled to survive after their bastion Sinjar was seized by the Islamic State (IS) group, forcing tens of thousands of people to flee.

The IS then pursued a brutal crackdown on the minority that included massacres, enslavement and rape.

According to the religious affairs ministry of Iraq's autonomous Kurdish region, IS has abducted more than 6,400 Yazidis. Around half have been rescued or managed to escape.

The fate of the others is unknown, although IS has lost most of the territory it seized in Iraq, including Sinjar.

Of the 550,000 Yazidis living in Iraq before the jihadists' 2014 assault, nearly 100,000 have left the country.

In March 2015, UN investigators said the IS assault on the Yazidis was a premeditated effort to exterminate an entire community -- crimes that amount to genocide. They called on the International Criminal Court to investigate.