1. Islamic State killed about 3,000 Yazidis - with more than half shot, beheaded and burned alive - and kidnapped about 7,000 women and children to become sex slaves or fighters in its 2014 siege.
2. According to community leaders, more than 3,000 Yazidis remain unaccounted for.
3. The estimated 550,000-strong Yazidi community are members of a Kurdish religious minority who have lived primarily in Iraq, Turkey and Syria.
4. The sect's beliefs combine elements of several ancient Middle Eastern religions.
5. Islamic State considers the Yazidi devil worshippers and has ordered them to convert or die.
6. Nadia Murad, a Yazidi rights activist and survivor of sexual slavery by Islamic State, won the 2018 Nobel Peace Prize.
7. International human rights lawyer Amal Clooney is working with Murad to prosecute Islamic State militants for crimes against humanity, including sexual abuse and enslavement of Yazidi women.
8. Islamic State militants have been driven out of the Yazidis' Sinjar heartland in northern Iraq, but many still live in camps, too afraid to return to their homes, charities say.
9. The persecution has forced thousands of Yazidis to seek asylum in Europe, with an estimated 60,000 in Germany.
10. Yazidi supporters have complained over delays in a United Nations probe, which last August began collecting evidence of acts by Islamic State in Iraq that may be war crimes, crimes against humanity or genocide.