Nejd

Najd or Nejd (Arabic: نجد ‎‎, Najd) is the geographical central region of Saudi Arabia in which twenty-eight percent of Saudis live. Najd consists of the regions of Riyadh, al-Qassim, and Ha'il.

Najdis were sometimes referred to in the past as the "dominant minority" in Saudi Arabia. Unlike Hejaz, Najd is very remote and had largely avoided falling under foreign control.

In pre-Islamic times the region of Nejd was settled by many tribes like the Kindites, Tayy and many others.

Led by Usma bin Luai the Tayy invaded the mountains of Aja and Samra from Banu Tamim in northern Arabia in their exodus from Yemen in 115 CE. These mountains are now known as Jabal Shammar. The Tayy became nomadic camel herders and horse breeders in northern Najd for centuries.

In the 5th century CE, the tribes of North Arabia became a major threat to the trade line between Yemen and Syria. The Ḥimyarites decided to establish a vassal state that controlled Central and North Arabia. The Kindites gained strength and numbers to play that role, and in 425 CE the Ḥimyarite king Ḥasan ibn 'Amr ibn Tubba’ made Ḥujr 'Akīl al-Murār ibn 'Amr the first King (Ḥujr) of Kindah. The Kindites established a kingdom in Najd in central Arabia unlike the organized states of Yemen; its kings exercised an influence over a number of associated tribes more by personal prestige than by coercive settled authority. Their first capital was Qaryat Dhāt Kāhil, today known as Qaryat al-Fāw.

...
Wikipedia