For most people Delphi is linked to the god of light, Apollo. But it was not always the case. The sanctuary has a history that begins long before the advent of Apollo. A history where women (and especially in their symbolic role of mothers) were in charge: The cult of Gaia, the Mother Earth, one of the first deities in all the cosmogonic myths of mankind, was attested at Delphi.

Anselm Feuerbach: Gaea (1875). Ceiling painting, Academy of Fine Arts Vienna, Austria.
Tradition and myth report that Delphi, originally called Pytho, was sacred to Ge or Gaia (Γη/Γαία = Mother Earth, the ancestral mother -sometimes parthenogenic- of all life) and that an oracle presided near a cave inhabited by the serpent Python, the son of Ge.
This first matriarchal period of Delphi is attested by the Delphic inscriptions found in place during the excavations. They mention the phrase «το ποτι γας ιαρον» (to poti Gas iaron) = what was once the sanctuary of the Earth. According to the archaeological research the sanctuary Ge would have been located a little northern of the present-day sanctuary of Apollo.
Another element that testifies the matriarchal power at Delphi is the name of Delphi itself. The ancient Greek word δελφύς (delfys), related to the name of Delphi, means womb. It’s exactly the shape of the valley of the Phaedriades when seen from the port Kirrha -the major access point to Delphi in ancient times.
Then Apollo arrives. The god of light establishes his power by killing the Python the son of Ge. He takes possession of the existent sanctuary and oracle of Gaia, the Mother Earth. At the same time asserts the patriarchal power: it’s then that the Ancient Greek society transitions from homometric (same mother) to homopatric (same father).

Sculpture by Pietro Francavilla of Apollo's first triumph, when he slew with his bow and arrows the serpent Python, which lies dead at his feet. The Walters Art Museum, Baltimore, USA
This brings the distribution of the families land to the male descendants and, gradually, at what is known as the Greek colonization (8th c. B.C.): the quest of new land lots. It’s the beginning of an expansion of the Greek world all over the Mediterranean sea, and the (new) Oracle of Apollo at Delphi takes the lead and has a vital role in it.