The founder of Arabia is Ya'rib bin Qahtan. Ya'rib (yacribiin) is named after a tree that grew there and is where the term 'Arab' comes from. They are the true Arabs as the only surviving descendants of the ancients. Descended from Hūd, Qaxdaan is the grandfather of Ximyar, Cumaan, Saba', Xadramowt etc who were men that have towns and countries named after them. The destroyed Arabs were the relatives and brothers of the Pre Qahtanis who lived in Yemen.The ishmalites are known as Arab almusta'rib. The Qahtanites are the oroginal arabs and are called arab al-ariba. Theres also third category, Arab al-baaida or 'the destroyed arabs', this category includes many arab clans that were greatly dwindled. In the arab al-ariba category are the banu imliiq according to 9th C ibn sa'd:
“'Imliq was the progenitor of the 'Imlags. And to them belong tall people of Barbar whose genealogy is as follows: Barbar Ibn Tamila (Taimallah) Ibn Mazarab Ibn Fárán Ibn 'Amr Ibn 'Imliq Ibn Ludh Ibn Sam Ibn Nuh. As regards Sunhajah and Kutamah, they are the descendants of Fariqis Ibn Qays Ibn Sayfi Ibn Saba (Sheba). It is said that 'Imliq was the first person to speak Arabic when his people had migrated from Babil. They along with the Jurhumites were known as al-'Arab al-'Aribah...Imlaq is the same as 'Arib and Tasim and Amim”.
-Tabaqat al Kabir of Ibn Sa'ad