You mislead people, when you only tell half the story. The truth is that it was actually a combined effort on the part of Nagabhata I of Gurjara Prathira Dynasty of North India, and the Chalukya Dynasty of South India that succeded in warding off the Arab forces:
The were two separate Arab invasions of India at that time. One crossed Saurashtra and was defeated at Navsari by the Lata branch of the Chalukyas. A separate, and most likely subsequent, Arab invasion crossed Rajasthan and was defeated in Malwa by the Gurjaras. Read your own source again. It mentions that Nagabhata defeated the Arabs at Ujjain (capital of Malwa, and center of the Gurjara kingdom), not in Gujarat.
Do you not realize that the state of Gujarat acquired its name from Gurjars?
The Abu mountains, the "abode" of the Gurjars, are located in South Rajasthan- right on the border with Gujarat.
I have relatives that reside in Mount Abu and I've visited that area when I younger (lived there for like 10 - 15 days at a time). Until recently, I actually didn't even realize, that Abu mountains fell on to the Rajasthan side.
That doesn't mean they are native to Gujarat. There are plenty of instances, in India and in other parts of the world, where a conquering people gives their name to the land they conquered. Rohilkhand is named after the Rohilla Afghans, but that doesn't mean Afghans are native to northeast UP. The Angles and Franks, both Germanic tribes, gave their names to England and France, respectively. The Bulgars and Turks, both originally from the Eurasian steppes, gave their names to Bulgaria and Turkey. I could go on.
The theory that the Gujjars originate in southern Rajasthan is just that - a theory. No one knows exactly where the Gujjars originally came from, because Indian sources are silent on them before the early medieval period. Even then, southern Rajasthan is not the same as Gujarat. Yes, there are cultural commonalities between them, just like there are cultural commonalities between any two neighboring regions in India. I have been to parts of rural Karnataka neighboring Andhra, and for all I knew I could have still been in Andhra. Both the Chalukya capital of Badami and the Rashtrakuta capital of Manyakheta are just a few kilometers from the border with Andhra Pradesh, and both states expanded into modern AP. But I would never say that these Kannadiga dynasties were indigenous to Andhra.
Also, until the late 8th century, most of Gujarat, with the exception of the southern regions (which were under Chalukya rule), was ruled by an independent dynasty based in Vallabhi called the Maitrakas. They were the descendants of a Gupta general who conquered Gujarat in the 5th century. It was only after the fall of the Maitrakas, that the Gurjaras brought much of modern territory of Gujarat under their rule.
Lastly, Gujarat is a part of North West India. To be precise, Gujarat is the Southern most region of the North West Indian corridor (or the Western most region of India). Gujarat is not South India.
No, Gujarat is not part of Northwest India. When historians and geographers talk of NW India, they are talking of Panjab, Kashmir, modern Pakistan, etc. Gujarat is considered to be part not of NW India but Western India, along with parts of Maharashtra.
What's astonishing is the fact that Gujaratis are having their history stolen. Moving on...
Seems like the opposite is happening to me. A thread is made with the title "Warriors of Gujarat", when most of the people mentioned simply lived and ruled in Gujarat, but were not native to it. By the same logic, people like Rudradaman and Mahmud Begarha could also be called "Warriors of Gujarat" with equal accuracy.
Actually, your very own source from the Chalukya Dynasty Wikipedia page, claims Chalukyas as being of Brahmin stock
I don't know which primary source document the author is relying on for evidence, because none of the primary sources I have seen describe the Chalukyas as brahmins. For example, the Chinese traveler Hsuan-tsang, who visited India in the 7th century, states that the Chalukya king Pulakesin II was a kshatriya.
Link:
Si-yu-ki: Buddhist Records of the Western World - Hsüan-tsang - Google Books
Brahmins are not native to South India. This same souce also goes on to state that the Solankis of Annila-Pattana (which is in Gujarat) have no connection whatsoever, to the Chaluklyas of South India. (Anahila-Pattana is in Gujarat.)
The author you quoted explicitly says that the Chalukyas, although Brahmins (according to him), were an "indigenous clan" and "belonged" to Karnataka. So either the author is wrong, or you are wrong, or both.
As for the origins of the Chalukyas/Solankis of Gujarat, I already mentioned in a previous post that they might have been Gurjars who migrated south and adopted the Chalukya name for prestige purposes (possibly via intermarriage with some Chalukya descendants). The theory of Gurjara origin seems to be popular with historians nowadays. Again, it doesn't really matter, because the Gurjaras are not native to Gujarat, either.