If those who live in desert regions are called Arabs then why the Rajasthanis (Indian subcontinent) who lives in desert area aren't Arabs?

The term "Arab" refers to a specific ethnic group with a shared cultural and linguistic heritage, primarily located in the Arabian Peninsula and surrounding regions. While many Arabs do live in desert regions, not all people who live in desert areas are Arabs.

Rajasthanis, who live in the desert region of Rajasthan in the Indian subcontinent, are not Arabs because they belong to a different ethnic and cultural group. Rajasthanis have their own distinct language, culture, and history that are separate from Arab identity.

It is important to recognize and respect the diversity of cultures and ethnicities that exist in the world, and not make assumptions based on geographical location or environmental factors.

The premise of your question is incorrect. Not all people who live in desert regions are called Arabs. The term "Arab" refers to people who speak Arabic as their native language and share a common cultural heritage originating in the Arabian Peninsula.

Rajasthanis, on the other hand, are an ethnic group from the northwestern Indian subcontinent, specifically the state of Rajasthan. They speak various dialects of Rajasthani, which is a group of Indo-Aryan languages, and have their own distinct cultural traditions.