The kahs-wan was a Vulcan rite of passage that young Vulcans were expected to accomplish.
It involved a trial into the desert where the Vulcan was expected to survive in order to be considered an adult. (TAS episode: "Yesteryear") The rules of this maturity test meant that it was a test of individual survival and as such, teamwork was forbidden. Those children that were wounded and discovered by another were left until the kahs-wan student returned home at the end of the suvival course where they reported the dangers faced by the other student. (TOS novel: The Vulcan Academy Murders)
Due to the nature of the rite, there were always casualties faced by those that participated in the kahs-wan. This left some eleven year olds unbonded and tradition allowed this to be the case. Following a suitable period of mourning, it was deemed appropriate by those families who had been widowed by the death of a mate at Vulcan's Forge to approach each other in order to partake in a new bonding. (TOS novel: Unspoken Truth)
Thousands of years ago before the Vulcan Reformation, Solor took part in a kahs-wan class that was led by his mentor Rovalat. However, the young Vulcans from ShiKahr were ambushed by members of the Te-Vikram Brotherhood who had slain members of the class. (TOS - Vulcan's Soul novel: Exiles)