In Tibetan Tantra, there is a ferocious female deity named "Mahakali", which can be translated as "Big Black" if it is directly translated. The name is well known. Many people think that this is the prototype of the big black Buddha, but it is not the case. Such cognition is decontextualized, and the details are described later. However, the statue of the Big Black Buddha does obviously refer to Tibetan Buddhism, including the drawing style, headgear and some instruments in the tunnel, etc., but only this has formal reference and re-creation with Tibetan Buddhism.
Secondly, in Hinduism, there is the job email list belief of "Black Mother/Time Mother", the details can be found here . These two, especially the latter one, are very close in name and form to the "Big Black Buddha Mother" described in this film, but the "Big Black Buddha Mother" itself does not exist in today's visible beliefs. It is worth mentioning that the "source of gods" described in this film should be: South India - Dianmi (Ali Sangpa) - Fujian - Taiwan Chen family. Dian Mi, a tantric system that spread in Yunnan, has now disappeared.
However, the source of the Buddha's mother (female ghost) belief has a very clear relationship with the popular "time mother worship" in South India. (Actually, Kālī in Sanskrit can be translated as "Black Mother" or "Time Mother". In this article, in order to avoid confusion between this god and the "Big Black Buddha Mother" in the movie, it is called "Time Mother". .) In addition to the details, you can refer to the above link, the handprint symbolizes the expression of opposition to the religious hegemony of North India, which I will describe later.