It looks like pre-Islamic India is a veritable treasure trove of every sort of information – with everyone visiting the country for knowledge, trade or whatever the reason. Kanheri Caves is a Buddhist Cave Complex near Mumbai which was active between 100 BC and 1000 AD or so.

There are a few very interesting inscriptions there, for example this Japanese one from Cave 66. Screen Shot 2018-08-08 at 17.16.24.png

The inscription reads
Nam-myo-Nichi-ren-D ai-Bo-Satsa”
“Namo Sad-dharma Pundarika Sutraya
Namo Nichirena Mahabodhisatvaya”

Nichiren was born in 1235 and it’s possible one of his followers who visited India inscribed it.
(The Journal Of The Bombay Branch Of The Royal Asiatic Society 1940 Vol.xvi)

Or these Pahlavi ones. The one below is one of the Pahlavi inscriptions.
Screen Shot 2018-08-08 at 17.22.28.png
These inscriptions seem to be done by visiting Parsis in the 11th Century and contains names of those who visited. This particular inscription reads as
In the name of God.
In the year 378 of Yazdakard, the month Avan and day Mitro (24th November 1009), there have come to this place the co-religionists Yazdan-panak and Mah-aiyyar, sons of Mitra-aiyyar, Panj-bhukht and Padar-bhukht sons of Mah-aiyyar, Mardan-shad son of Hirad-Bahram and Hirad-BAhram, son of Mardan-shad, Mitra-aiyyar son of Bahram-panah and Bahram-panah, son of Mitra-aiyyar, Falan-zad and Zad-sparham sons of Atur-mahan, Nuk-mahan, Din-Bahram, Bajurg-Atur, Ibram-mard, and Beh-zad sons of Mah-bazae, and Bahram-panah son of Mitra-bandad. In the month Atur, Auharmazd son of Avan-bandad died.
(The Indian Antiquary Vol. 9)

The Pahlavi inscription is even interesting because Persia and Zorastrianism has already been broken and we are seeing Zorastrians in India three hundred years after Zorastrianism was almost extinguished in the whole world.