Seems there is a pretty good chance that the origin of zero is still Indian and was adopted by the Khmer just as they adopted the Indian calendar.
ॐ पूर्णमदः पूर्णमिदं पूर्णात्पूर्णमुदच्यते ।
पूर्णस्य पूर्णमादाय पूर्णमेवावशिष्यते ॥
ॐ शान्तिः शान्तिः शान्तिः ॥
Om Puurnnam-Adah Puurnnam-Idam Puurnnaat-Puurnnam-Udacyate | Puurnnasya Puurnnam-Aadaaya Puurnnam-Eva-Avashissyate || Om Shaantih Shaantih Shaantih ||
Rough Translation:
That (god) is complete(puurnnam), this living being is complete. From completeness emerges completeness. When this completeness (living beings) emerges from that completeness (god), only completeness remains.
This verse describes God. But it can also be describing concept of zero and infinity. Buddhist philosophy emerging in 500 BCE is based in shoonyata[1] (nothingness) so concept of zero was definitely known for a long time.
As far as mathematical applications are concerned, we can't say for sure as a lot of knowledge was lost to invasions which specifically targeted universities like Nalanda[2].
Hindus imagined time scales of microseconds to trillions of years which in IMHO difficult to imagine without zero based mathematics[3].
Having said that there are a large number of manuscripts in the hands of small groups and families are yet to be discovered so these dates.
[0] https://en.wikipedia.org/wiki/Isha_Upanishad [1] https://en.wikipedia.org/wiki/%C5%9A%C5%ABnyat%C4%81 [2] https://www.myindiamyglory.com/2017/09/11/nalanda-9-million-... [3] https://en.wikipedia.org/wiki/Hindu_units_of_time
1305
+ 0935
----
2240
((5-5)+2)*0 = (0+2)*0 = 2*0 = 0Shukla Yajurveda[0] conservatively estimated to be written in 1200- 800 BCE period in 17.2.20 constructs powers of 10 upto a billion by names by adding shunya successively to 10.
That area first came under Indian influence centuries before these dates. Some parts of the country, Chenla, were dependent on states in Java and Srivijaya (the one mentioned in the article) later on. The Indian cultural sphere as a whole covered a huge area and the Subcontinent itself certainly did not have a monopoly on culture there.