The Najd mentioned in the narrations of the Prophet Mohammed peace be upon him – is IRAQ not what is now called Najd as Riyadh in Saudi Arabia.
“The najd is in the direction of the east, and for the one who is in Madeenah then his Najd would be the desert of IRAQ and it’s regions for this is to the east of the People of Madeenah.”Ibn Hajr quoted al-Khattabi
Historian Ali ibn al-Athir, who had frequently traveled to Iraq during the era of Saladin and had written his monumental work al-Kamil fi at-Tarikh (The Complete History), writes in his work ‘al-Nihâyah’:
“Najd is the highland region. This name is given to area beyond the Hijâz towards IRAQ.”
Ibn Umar reported: The Prophet, peace and blessings be upon him, said, “O Allah, bless us in our Syria. O Allah, bless us in our Yemen.” He repeated it and on the third or fourth time, they said, “O Messenger of Allah, and in our IRAQ.” The Prophet said, “Verily, from there will appear upheavals and tribulations and from there will rise the horn of Satan.” -(Tareekh Damishiq of Ibn-Asakir pg.571 and more)
The above hadith has a difference in wording where the man asks “and our NAJD as well as the wording mentioned above where he asks “and our IRAQ”.
Ibn Umar reported: I saw the Messenger of Allah, peace and blessings be upon him, pointing in the direction of ‘IRAQ and saying three times, “Verily, the tribulation will come from there. From there will rise the horn of Satan.” -(Musnad Ahmad 6266)
Narrated Ibn Abi Nu’m: A person asked `Abdullah bin `Umar whether a Muslim could kill flies. I heard him saying (in reply). “The people of IRAQ are asking about the killing of flies while they themselves murdered the son of the daughter of Allah’s Messenger (ﷺ) . The Prophet (ﷺ) said, They (i.e. Hasan and Husain) are my two sweet basils in this world.” -(Sahih al-Bukhari 3753 )
The above narration says, those who killed the grandsons of the Prophet. And it goes without saying, the people of Iraq martyred the grandsons of the Prophet rather the people of Riyadh.
From all the above narrations, it’s quite evident and clear that “Najd” refers to Iraq not Saudi Arabia.