Among all those who suffered under ISIS, the Yazidi people, and particularly its women, endured most appalling traumas. 
With most Yazidi populations living in north Iraq, they are ethnically Kurdish, speaking Kurmanji dialect; major locations include the pilgrimage site of Lalish and Mount Sinjar to the west.
While the fate of the Yazidis under ISIS is shocking, they have long been persecuted, with massacres during the Ottoman empire and tribulations under Saddam. For social and religious change over recent decades, suggesting the region’s troubled history and complex economic and political context, do watch this documentary by Eszter Spät, filmed on the eve of the genocide, about the ritual tour of the sacred peacock standard—with the hymns of the qewwal ritual specialists accompanied by frame-drums and flutes:
For the oral tradition, see e.g. here, and for a detailed textual study,
- Khanna Omarkhali, The Yezidi religious textual tradition: from oral to written (with CD-ROM, 2017).
Under the ISIS regime the Yazidis were executed, abducted, enslaved, raped. With many survivors now in displacement camps, refugee communities are also quite widespread, such as in Germany and Nebraska.
In extremis, culture may lie dormant (cf. Blind minstrels of Ukraine, and the ongoing onslaught on the Uyghurs), or adopt exceptional forms (cf. the Cultural Revolution in Tibet). Now a project from the AMAR Foundation is working with Yazidis to support and document their musical culture, and earlier this month they brought a group of male qewwals and female singers to England to perform for select audiences in Oxford and London (see e.g. here and here).
While media coverage tends towards clickbait headings like “rescuing ancient music”, suggesting an unspoilt, pristine culture destroyed by a single apocalypse (cf. China), the Yazidis’ fate under ISIS is but the latest and most extreme instance of their persecution.
And music is not a thing, it’s what people do. So as AMAR recognizes, the whole maintenance of Yazidi culture is part of a complex long-term endeavour, depending on the rebuilding of communities with a modicum of stability that require ceremonial and entertainment activities and have scope to practise them. Cultural foundations may play a certain role, but most of what such societies need is beyond their powers. The task is not to become the latest flavour-of-the-month on the world music bandwagon; foreign tours can help promote their international profile, but the regeneration of Yazidi culture depends on their’ own efforts in their homeland, and in the camps where they have been relocated. This was filmed in July 2019 at Khanke displacement camp, Duhok:
As Bruce Jackson observes about “salvage” fieldwork, it’s always too late. The fate of the Yazidis may be an extreme case, but much of this applies to the cultures of the diverse ethnic groups and communities throughout the war zone. For instance, what will become of the rich musical and ritual culture of Aleppo, whose fall is so movingly documented in For Sama? And alongside traditional music, popular genes (rap, hip-hop, and so on) are a major part of the identities of such ethnic and political groups.
For Kurdish ritual culture, see here.
 On wiki, see here, and for Yazidi religion, here. Apart from the outstanding journalism of Channel 4, I also admire the sincerity of reports by Stacey Dooley; in this programme she spent time with an all-female Yazidi battalion. Among numerous media articles from before and since the 2014 genocide, see e.g.