Cultural Arts The Indian in the Filipino

Apparently even Taiwanese Aborigines like the Atayal have around 6% North Indian admixture according to the latest DNA studies Reconstructing the Human Genetic History of Mainland Southeast Asia: Insights from Genome-Wide Data from Thailand and Laos | Molecular Biology and Evolution | Oxford Academic (oup.com)

We finally built admixture graphs using AdmixtureBayes, and then further investigated these admixture graphs with qpGraph. To begin with, we built a backbone admixture graph with the outgroup Mbuti, N_Indian, and the following representative East Asian groups: AA-speaking Cambodian, AN-speaking Atayal, TK-speaking Dai, HM-speaking Miao, and ST-speaking Naxi (fig. 5A). Another f4 test with Amis, She, and Yi as alternative AN, HM, and ST representative groups, respectively, was performed to verify that our choice of representative groups is not biased in distinguishing the fine-scale relationships within each language family (supplementary fig. 13, Supplementary Material online). In the backbone graph, the first split separates the N_Indian from the East Asian groups, then the Naxi are separated from the other groups. The ancestor of Atayal and Dai is admixed from ancestors of N_Indian and Miao with 6% and 94% ancestry, respectively. The ancestor of Cambodian is admixed with 73% ancestry from the ancestor of Dai and 27% from the ancestor of all East Asian groups. The graph of AA groups (fig. 5B) includes several admixture events, and indicates that the Khmu_Katu_AA and Palaungic_AA subgroups are more closely-related, while the Monic_AA subgroup is distinguished from these by N-Indian-related ancestry, in agreement with the results of other analyses (figs. 2 and 4A).

I've always been fascinated with India, and how India influenced Southeast Asia (and Asia in general) including the Philippines.  But there's always bits and pieces of the history missing.  Here's some questions:

1)  What social or political structure did we inherit from India prior to the Chola Empire's invasion of Southeast Asia?  Some has said that the term "datu" is Indian in origin, but is it really?  Of course terms such as rajah and maharlika are perhaps more obviously Indian.  But the question is why adopt these honorifics, when you could simply use native terms?  Now Sri Vijaya is obviously an Indian influenced term, but why use that term?  We borrow words from merchant traders, but to the point of adopting political honorific terms?  Again, I'm talking pre-Chola Empire invasion of Southeast Asia.  What makes the social or political structure from India different from any political structure?  What are the key features of a rajahnate or datu kingdom (assuming that term is Indian in origin)?  Now some will say that it's likely the spread of Hinduism (or various "sects" of it such as Shivaism) or Buddhism, but it begs the question how did these religions spread and replace local religions?  I've read that the local rulers of present day Indonesia, Malaysia, and Philippines likely converted to Hinduism and/or Buddhism, and it's from the elite caste that the religion spread downward to the masses.  But it begs the question, why would local leaders adopt Hinduism and Buddhism in the first place?  Again, I'm talking about pre-Chola Empire invasion period.  

2) We adopt Hinduism and Buddhism, but why not yoga practices?  Sure some heavily Indianized regions such as Bali practice yoga today, and Javanese practices such Kejawen have some yogic influences, but what about much of Island Southeast Asia?  Yoga is a very complex practice, and it is a very ancient practice.  It involves asanas (body positions) and stretching, breathing techniques or methods, and mental and spiritual concepts such as obtaining Nirvana.  These concepts and techniques don't seem to have migrated to the Philippines or at least survived today.  If yoga was ever introduced to the Philippines, why does it not exist in at least a fragmentary form?  I should also mention that there are several types of yoga, but none seem to exist today in an even fragmentary form.  This has always been a mystery to me.  Wouldn't Hinduism and Buddhism promote yogic practices?  Or was it largely exclusive to the rulers and elites, and somehow did not pass downward to the masses prior to the arrival of Islam and Christianity, or perhaps it did pass down to the masses but they were eradicated over time?  But wouldn't we still have some evidence of yogic practices or concepts even in a fragmentary form among the descendants of the elites or among the general population?

3) After the initial Austronesian expansion, did Austronesian civilization in general collapse?  If Austronesian civilization was healthy and strong, why would it adopt foreign political structures, religions, and etc.?  Sure even a healthy and strong civilization learns and adopts from others, but it appears that Indian civilization may have played a key role in revitalizing Austronesian civilization, at least that's what it appears to me when you look at structures such as Borobudor and Prambanan, or the various kingdoms and empires with Indian based names such as Sri Vijaya and Majapahit, and the spread of Hinduism and Buddhism.  Why was Indian civilization so advance and perhaps more advanced in general compared to Southeast Asia in the first 1,200 years after 0 C.E.?  What allowed India to become advance to the point that it influenced and perhaps revitalized Austronesian civilization or at least helped it significantly?