The Tomb of the Gods
The chalice dungeons are where everything began for the civilisation of Yharnam. A fellow hunter, Alfred, tells us that “the tomb of the gods, carved out below Yharnam, should be familiar to every hunter.” These labyrinths are the remnants of another culture, the Pthumerians, long-gone though not quite extinct. At some point the pre-Yharnamites discovered a chalice that granted access to the Pthumerian labyrinth and began exploring. It was not empty.
Though it was filled with crazed and universally hostile beasts, and terrors even worse, the explorers pushed on regardless – and discovered remnants of what appeared to be gods. They returned with treasures, mysterious lifeforms and other strange organic debris. A great institute of learning, Byrgenwerth, was founded to explore and collate as much as it could. Here are our beginnings.
Alfred tells us that a group of young Byrgenwerth scholars eventually discovered a “holy medium” – a means or channel of communication – within the tomb, and that this would later lead to the founding of the Healing Church and blood ministration. The latter is what Yharnam is best-known for in the time of the game.
But one more detail. If the player explores far enough in the Chalice Dungeons s/he will discover the Pthumerian Queen. This woman is also seen at various points during Bloodborne's main storyline, and the emphasis is on her lost child.
The Pthumerians had superior knowledge of the Great Ones, and their Queen was pregnant with a child that was either stillborn or died soon after birth. Later in Bloodborne the player will obtain a third of an umbilical cord which states:
“Every Great One loses its child, and then yearns for a surrogate, and Oedon, the formless One, is no different. To think, it was corrupted blood that began this eldritch liason.”
The Pthumerian Queen bore and lost the child of formless Oedon. And so when the explorers of Byrgenwerth found the Queen, they found the blood of a Great One – a wondrous substance, or so it seemed.
The Pthumerian Queen's name was Yharnam. A city was built atop the labyrinths, and named in tribute. The eldritch liason had begun.