There is not a lot of research regarding Buhid people or their script. This researcher was unable to find sources dictating the origin of the the script and has listed the location of Buhid communities from Colin E. Tweddell's anthropological survey in 1970 for the earliest attested location.
Unicode Chart 
Maps
Https://scriptsource.org/cms/scripts/page.php?item_id=script_detail&key=Buhd
DISCLAIMER: This script is still being researched
Data
| Alternate Names | Mangyan Babayin, Surat Mangyan, Bangon |
|---|---|
| ISO 15924 | Bhd 372 |
| Type | Abugida |
| Family | Insular Southeast Asian |
| Direction | LtR |
| Diacritics | Yes |
| Contextual Forms | No |
| Capitals Used | No |
| Glyphs | 18 |
| Inventor | Unknown |
| Earliest Location | Sumagui, Phillipines (also Manihala, Tangon, and nearby streams northwest of Bongabon city) |
| Earliest Date | 1604 CE |
| Latest Date | Present |
| Ancestry |
|
Overview
Bibliography
| Author | Year | Publication | Publisher |
|---|---|---|---|
| Calapang, Emereciana Lorenzo | 2014 | Reviving the Hanunuo and Buhid Mangyan Syllabic Scripts of the Philippines | Mangyan Heritage CEnter, Inc. |
| Changizi, Mark A and Shinsuke Shimojo | 2005 | Character Complexity and Redundancy in Writing Systems over Human History, Vol. 272, No. 1560 (Feb 7, 2005), p. 267-275 | Proceedings: Biological Sciences |
| Coulmas, Florian | 1999 | The Blackwell Encyclopedia of Writing Systems, 313-349 | Blackwell Publishing |
| ISO/IEC | 2020 | The Unicode Standard, Version 13.0, p. 686-688 | Unicode, Inc. |
| Tweddell, Colin E. | 1970 | The Identity and Distribution of the Mangyan Tribes of Mindoro, Philippines; Vol. 12, No. 6 (Jun., 1970), pp. 189-207 | Anthropological Linguistics |