Do you have any reading recommendations for learning about the Tibetan ideas that were Ship-of-Theseus-ed into tulpamancy?
It's probably not what you want to hear, but no, not really. A lot of Tibetan practices and ideas are orally transmitted and directly taught from one person to the next and that is very intentionally done. Beyond general hand waves at the practices which aren't particularly well summarized into written sources and publicly available, a lot of the concepts you have to interact with and engage with directly from someone within the culture.
I was talking to a POC friend about this and how its a thing that I find frustrates a lot of white / western people, but its an orally transmitted culture / tradition by design and when people talk about if its an open or closed religion, I think theres a second dimension that people don't consider - private or public religions / practices.
Some traditions are public - in terms of the majority of their information - but closed in terms of who can practice. Judaism is an example of a closed public culture / tradition / religion.
For the record, I'm not Jewish so if I got anything wrong here, anyone is free to correct me. This is my extent of understanding and I may be wrong, but save for the deeper more niche knowledge, a lot of general information about Judaism beliefs, ideas, rules, philosophies, etc are out there for people to easily read and the culture typically doesn't have too much of an issue letting people who aren't Jewish know about what Being Jewish entails. People are welcome to look into and observe and learn about Judaism pretty freely regardless of if they are Jewish or not. That said, not everyone can claim to be Jewish and not everyone can pick up Judaism (or at least not easily without going through a lot of hoops).
Others are private - in terms of the majority of their information - but open in terms of who can practice. Tibetan Buddhism is an example of an open private culture / tradition / religion.
When it comes to Tibetan Buddhism, anyone is allowed to choose to study and practice Tibetan Buddhist. (There is some level of disagreement among Tibetan Buddhists about this, but generally speaking) Anyone is allowed to take some of the lessons and themes found in a Tibetan Buddhist perspective and use it in their life. Its open to people who want to engage in Tibetan Buddhism to engage with Tibetan Buddhist.
With that being said, MUCH of the information that differentiates it from Buddhism in general, Zen Buddhism, Theravada Buddhism, etc (and there is a good amount) is largely closed behind actually talking to a Teacher and having a mentor in the practices and learning about them in person study groups and discussions and it's really looked down upon to share or talk about any of the practices in depth without permission from the person who taught you - let alone write it down where it is accessible to all.
Tibetan Buddhism intentionally adds barriers to understanding / learning and intentionally makes even the texts that could be considered equivalent to the 'Bible' to be very esoteric, obscure, and confusing as a way to make it so that people who do have the book still have to consult with their teacher to really understand and decode it.
The information is not meant to be publicly available beyond maybe a hand wave general idea - enough so that even I don't know the details of the specifics because I have yet to have a place in my life where I can really dedicate myself to the study that would be asked of me.
Even if I did, I wouldn't write it down or type it out because that would be a disrespect to the practice.
I'm not explaining this to scold you or anything, but more so because I think its a good opportunity to put it out there for people in tulpacourse that you will not and cannot find good resources about the original practices inspiring Modern Day Tulpamancy because by the nature of it, anything that is written down is likely from an not credible source as writing it down is going against the very core principle that anyone who attended a teaching would know is strictly forbidden. Anything written down is either wrong or actively doing a massive disrespect to a culture that has been around for over a millennia as a primarily orally transmitted culture.
I deeply appreciate that about Tibetan Buddhism and so I think anyone who isn't a Tibetan Buddhist and isn't willing to dedicate years to studying it from a teacher ideally of the homeland culture who has dedicated their life to the lessons need to respect that they are unlikely to know or learn about it if their interest is just "curiosity".
I myself do not really consider myself an Actual Tibetan Buddhist because I have not actively dedicated the time to studying specifically Tibetan Buddhism - but it is something I want to do when life has a good place for me to do so. For now, I'm a general Mahayanan Buddhist that would really like to study Tibetan Buddhism.
