Are the descendants of prophet Muhammad among the ruling family of Saudi Arabia?

 No they are not.

The House of Saud originated from the Nejd in central Arabia. The Prophet Muhammad never lived in the Nejd, but he lived his whole life in the Hejaz in Western Arabia, in the cities of Mecca and Medina.

However the ruling families of Morocco and Jordan descend from the Prophet Muhammad’s family.

The House of Hashim is the ruling family of Jordan. They are descended from the Prophet Muhammad’s family through his daughter Fatimah, and all Hashemites descend from Muhammad’s ancestor, who was named Hashim.

It used to rule Iraq, Syria, and even the Hejaz, where they originated and lived their entire lives from the 5th century until their kingdom was destroyed by the House of Saud in 1925.

The Alouite dynasty is the ruling family of Morocco. They are descended from Ali, a cousin of the Prophet Muhammad. The founder of this royal family was Sharif ibn Ali, who lived in the Hejazi town of Yanbu which is a town near Medina.

Sharif bin Ali descended from Ali bin Abi Talib, again who was a cousin of the Prophet Muhammad. Sharif bin Ali moved out of the Hejazi town of Yanbu to immigrate to Morocco, and his descendants got power in Morocco which led to the founding of the Alouite dynasty.

So again there is no way the House of Saud in Saudi Arabia originated from the Prophet Muhammad’s family. They came from the Tribe of Anazzah, a tribe that lived in the Nejd.

The Hashemites and Alouites were from the Quraysh, which was the tribe of the Prophet Muhammad.

However, there are still a lot of descendants of the Prophet Muhammad’s family throughout the world, mostly in the Middle East.