Over the last few years, Saudi Arabia has upgraded the equipment and training of its armed forces. Actually, there are two, separate, armed forces. Overall, the Saudi military has about 200,000 troops. But 75,000 of those belong to a separate force, the National Guard. These are organized into eight brigades (three mechanized and five infantry, for a total of 32 battalions.) There are also another 24 battalions of National Guard reservists. The National Guard is well armed and trained, all of them.
The National Guard were originally, a century ago, the Ikwhan. These were truly holy warriors, being Bedouin fighters dedicated to the strict Wahhabi form of Islam, and killing enemies of Islam. The founder of Saudi Arabia used the Ikwhan as his shock troops. In the 1930s, the new kingdom of Saudi Arabia had to crack down on the Ikwhan , who were continuing to raid outside the kingdom, since there were no more enemies inside the kingdom to fight. The Ikwhan was shut down (with some bloodshed), and some of its members helped form the National Guard.
The National Guard has about a thousand wheeled armored vehicles and some artillery. In recent years, some $6 billion was spent on new wheeled armored vehicles, and lots of neat gadgets like night vision gear and new communications equipment. Bedouins love this stuff, and adapt quickly to it.
Nearly all the National Guardsmen troops are Bedouins, usually from tribes that have been historical allies of the al Saud family. The king considers the Guardsmen his boys, and takes good care of them. If a Saudi needs a favor from the king, he's much more likely to get it if he is, or was a National Guardsman.
About a third of the National Guard are especially selected from the most loyal (to the royal family.) This is the "White Army" (for the traditional white robes of the Bedouins). The most loyal force is the 2,000 man Royal Guard Regiment. These, as the name implies, are responsible for the day-to-day security of the king and his immediate family.
When Saudi Arabia was put together 80 years ago, many tribes were encouraged to join the new kingdom by force, or lots of arm twisting. These groups continue to hold a grudge (a venerable Middle Eastern custom), and the most hostile of these are not recruited for the National Guard.