It is a Hindu ritual practiced in northern Kerala and some parts of Karnataka.
A Theyyam, also known as Kaliyattam or Tira is a ritualistic performance where pantheistic deities — goddesses in most part — are summoned to the body of the performing man.
The form as well as the performance are known as Theyyam.
The Chamundi Theyyam is performed by the Pulayas, a Scheduled Caste, who consider Goddess Chamundi as the protector of the Thimiripadam paddy land.
The Theyyam is performed annually during the start of the Malayalam month of Thulam (mid-October-mid-November).
There are about 456 types of Theyyams documented.
Theyyam is mainly performed by males, except the Devakkoothu theyyam which is the only Theyyam ritual performed by women.

Key facts about Chamundi Theyyam:

Chamundi Theyyam is a popular ritual folk dance performed in the Kasargod and Kannur districts of Kerala.
It is an annual religious event held at various temples and shrines dedicated to Goddess Chamundi or Chamundeshwari.
The dance is performed by people from the Vannan community who don elaborate costumes, face masks, headgears and body paint during the act.
It involves invoking and glorifying Goddess Chamundeshwari, who is considered as a fierce incarnation of Devi in Hindu mythology.
The performers reenact tales of the Goddess' bravery and victory over demons like Mahishasura through their vigorous dances and ritual movements.
The act features colorful props like shields, swords and tridents that add to the divine imagery and symbolism.
Traditionally, the Theyyam starts late in the evening and continues through the night until daybreak the next morning.
It involves a trance state where the performer takes on the spirit of the deity and seeks blessings for all devotees.
The Chamundi Theyyam is accompanied by traditional drummers or chenda melam artists throughout the performance.
While the dance remains mostly the same, costumes and painting styles differ based on the shrine or region of performance.
The Chamundi Theyyam is recognized as a protected ritual under the UNESCO Representative List of the Intangible Cultural Heritage of Humanity.