Start here: give me an explanation for Kailasa Temple and how it was built. The entire temple was built by carving out a mountain by removing 400,000 tonnes of rock. Please explain how so much rock was removed from the face of the mountain using just chisels and hammer. I'll be waiting for a proper scientific answer to my question. To know what the Kailasa Temple is and its breath taking architecture you can watch the video I linked below [1]. Remember that this entire Temple was supposedly constructed in just 18 years.

[1]: https://www.youtube.com/watch?v=B2Jl4HNDixc

> How did they lost it? Against what?

You do realize the Hindu civilization (more specifically Sanatana Dharma) is the only Ancient Civilization that is currently existing? Most of the other Civilizations (like Egyptian, Mayan, Greek etc) that co-existed with us were wiped out by either natural disasters or with the rise of Abrahamic Religions. Libraries were burnt down. Most of the structures destroyed. Why do you think the Sphinx in Egypt has its nose cut off? Who destroyed these beautiful super structures? If you truly are inquisitive you will find your answers. They are the same ones who destroyed the Buddhas of Bamiyan. They are the same ones who burnt the Libraries of Alexandria to the ground. The same ones who destroyed the Libraries of Takshashila and Nalanda. It is quite rich to question "where is the evidence" after destroying evidence. We have somehow managed to collect and preserve whatever remaining piece of evidence we have and tried to reconstruct lost history through it. We ofcourse do not have complete knowledge of what was lost.

> Why didn't the contemporary people to the Indians depict them as semigods?

All Ancient Religions had concepts of God and a family of Demigods. Take Greek or Egyptian or Mayan or Hindu. Even Zoroastrians had scriptures that were similar to Vedic scriptures. Most of these are gone now except the Hindu Civilization. We are the last ones who managed to preserve some of the Knowledge despite repeated invasions. Even we have lost major portion of our Knowledge as our scriptures reference texts which no longer exist today. It is extremely sad/unfortunate.

> No wonder people sees Indian nationalism as a joke.

Which people are these? I haven't met anyone except very few people who has an issue with genuine curiosity/understanding of what the Ancients did/believed in and implemented. I feel you need to come out of being so close-minded. It is antithesis to someone who claims to believe in science. Science is not dogmatic. If it was dogmatic we would have never moved on from Newton's theory of absolute time to Einstein's explanation of relativistic time. And you can get ideas from anywhere. There is no reason to dismiss something as "pseudoscience" just because you are unable to understand it the right way. This is what the Church did in the medieval ages to scientists like Galilio and Copernicus. Don't emulate such practices. Be broadminded/inquisitive enough to question and reason rather than outright dismiss an entire field of research as "pseudoscience".

> Kinda like the Nazis when they had "time-travelling" UFO tech mixing pseudoscience with esoteric stuff...

Jokes on you because most scientists of that era actually studied Dharmic scriptures. Erwin Schrödinger, Werner Heisenberg, Robert Oppenheimer, Niels Bohr and Carl Sagan are some of the names that come off the top of my head.

All of them read some portions of the Dharmic scriptures, specifically Upanishads and Bhagavad Gita, that shaped their understanding of metaphysical nature of Creation as well as existence.

It is very unfortunate that people today do not have the same curiosity as what these excellent scientists of the previous Era had in expanding their conscious thoughts beyond what is taught in academia. Even what is currently taught in academia is just a synthesis and solidification of what the Ancients taught us through generations. You study Dharmic scriptures and you'll find a lot of foundational concepts of science described in great detail. Ofcourse you would first need to be open minded to do that.