Hejaz
Historically, the Hejaz has always seen itself as separate from the rest of Saudi Arabia. The Hejaz is the most populated region in Saudi Arabia; 35% of all Saudis live there. Hejazi Arabic is the most widely spoken dialect in the region. Saudi Hejazis are of ethnically diverse origins.
South Arabia
The frontiers of South Arabia as linguistically conceived would include the historic peoples speaking the related South Arabian languages as well as neighboring dialects of Arabic, and their descendants. Anciently, there was a South Arabian language, which was borrowed by Ethiopia.