Why did no one conquer Arabia?

Reasons for the Lack of Conquest in Arabia

The Persian Empire found it challenging to expand into Saudi Arabia due to the harsh conditions of the Arabian Peninsula, which was predominantly a barren wasteland. It was inhabited by hostile nomadic tribes engaged in constant warfare, with only a few merchant cities scattered amidst the intricate network of trade routes. Maintaining control over such a territory would have proven difficult for any foreign occupying force, and there were limited rewards to justify the effort of conquest.