It was me who wrote about this.
In certain African cultures, sand is indeed inserted in the vagina when a couple gets married. This is done by friends and relatives of the bride as a “rite of passage” and its purpose is indeed to make sex dry/painful for BOTH partners. In males, the foreskin will be pulled back by the dry sand and the frenulum will tear, which causes bleeding (this is the so-called “male defloration”). In females, the hymen will tear and the sand will cause little scars, adding to the bleeding. The couple has no privacy and needs to have sex in front of their family so they can see the blood. As a researcher, I’ve seen videos of thise rites and the couple is in so much pain the images are difficult to watch.
I wrote about this because afterwards, lots of those young women end up with vaginismus due to their painful first experience.