Kalifee v'rekor was an ancient ritual made by early Vulcans which was considered barbaric in the later ages. Also known as "battle with the desert", it was a way of winning a quick death without burdening one's clan and involved a person walking into the harsh environment of the world where they would die. This was typically made by those who had lost everything in their lives or had been greviously wounded which prevented them to function in society.
This act was typically done by members of the Te-Vikram Brotherhood. (TOS - Vulcan's Soul novel: Epiphany)