Too much contradiction, huh? What am I? An ignorant or knowledgeable? You seem perplexed. Like you are perplexed about South Asia and SE asia. Just look at your topic of OP. Are you sure you know the difference between SAARC and ASEAN?

Buddha was of an "arya" race. No doubt about that at all, And, you don't have to time travel to his era to know that. Just read the history of early Buddhism. Who were early Bhikkhus that spread Buddhism? Kshatriya princes of many royal houses of Bharat Barsa, mainly nowadays mainland India. I am not talking about SE asian countries. [BTW I am aware of the fact of hindu rule in Cambodia, Thai, Indonesia, etc.]

Buddhism started flourishing from Magadh, present day Patna, ruled by Nand dynasty. Almost all Kshatriya houses around that time and after followed Buddhism. It was almost communal. Be it Gupta, Maurya, Sen, Pala, Kushan etc.The abolition of Nanda Dynasty has to do with clash between Buddhism and Ajivika (then a branch of Brahmanical school of Hinduism). Nanda kings decreed his subjects to provide alms only to buddhist Bhikkus, mostly the Kshatriya Kumaras, and not to brahmans. The main reason Chanakya abolished the Nanda rule from Magadh was flourishing of Buddhism. (Then Nepal also helped Chanakya and Chandragupta to dethrone Nanda king. That means Nepal did not have buddhism, else Nepal would not go against Magadh. Nepal then was allegedly and mythically ruled by Kiratas) There was clash between Kshatriyas and Brahmans (Hindus). No offense, but I am highly skeptic Tharus would be regarded Kshatriya then. By any means. Seriously. Even Khas became Kshatriya only in the 16th century. Tharus also live in Uttaranchal region of India. Just read what Tharus are called there. Buddha was a Bihari Kshatriya, in present day context. Bihar was the center of the world, academically and intellectually around and after the time of Buddha. Nalanda? Does bell ring. You need not be a genius to understand or make an educated guess that Buddha was not a tharu.

Mahavira was also a Kshatriya prince of present day Bihar, who was in the footsteps of another kshatriya prince Buddha. Are you also going to say Mahavira was also a tharu?

And, I hope next time you keep a healthy discussion. No personal attack.