They're even more qabilist than us, times 10.You can marry a saudi woman, but this is the complication. You can't marry in your own country but Saudi Arabia.
Some Arabs you have to stay away that don't marry with other Arab tribes. Because its a part of their daqan. Same case as Somalis its a hard case for a Majerteen to marry a Habar gidir, we even marry other tribes like for example Isaaq and Cisse. Arabs and Somalis same stuff.
I learnt the Ajanbi does not imply for hon arabs but rather if your saudi you can call a qatari an Ajanbi or Yemeni. Its a word that anyone can use.