Arabs were defeated in 738 A.D. by

The Battle of Rajasthan is a battle (or series of battles) where the Gurjar Hindu alliance defeated the Arab invaders in 738 CE The final battle took place somewhere on the borders of modern Sindh-Rajasthan. Following their defeat the remnants of the Arab army fled to the other bank of the River Indus.The main Indian kings who contributed to the victory over the Arabs were the north Indian Gurjar Emperor Nagabhata I of the Pratihara Dynasty and the south Indian Gurjar Emperor Vikramaditya II of the Chalukya dynasty in the 8th century.

Source : thehistoryindia.blogspot.com