I'm well familiar with the area. Lived a couple of hours away from Yemen. The one road we used to take to the Red Sea took us within a half hour of the Saudi-Yemen border. At the market there we would see the “flower people”, a local tribe. They dressed different from the Saudis and Yemenis. Wore a band of flowers around their head. The Saudis I talked to were afraid of them as they said the flower people will mess you up with their knives.
The story went that back in the mid 90s, there was a treaty where the Saudis had to return a large amount of the border territory once owned by Yemen. Oil was found there so the Saudis didn't give it back. Yemen tried to take it and got their clocks cleaned. Yemen makes a move every so often to grab it back and loses.